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cclauss merged 7 commits into from
Apr 8, 2023
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Queue implementation using two Stacks #8617

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49ce661
Queue implementation using two Stacks
amirsoroush Apr 7, 2023
37bd353
fix typo in queue/queue_on_two_stacks.py
amirsoroush Apr 7, 2023
1da0297
add 'iterable' to queue_on_two_stacks initializer
amirsoroush Apr 8, 2023
100ec02
make queue_on_two_stacks.py generic class
amirsoroush Apr 8, 2023
d9accd5
fix ruff-UP007 in queue_on_two_stacks.py
amirsoroush Apr 8, 2023
953660b
enhance readability in queue_on_two_stacks.py
amirsoroush Apr 8, 2023
a8eb743
Create queue_by_two_stacks.py
cclauss Apr 8, 2023
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115 changes: 115 additions & 0 deletions data_structures/queue/queue_by_two_stacks.py
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
def __init__(self, iterable: Iterable[_T] | None = None) -> None:
"""
>>> QueueByTwoStacks()
Queue(())
>>> QueueByTwoStacks([10, 20, 30])
Queue((10, 20, 30))
>>> QueueByTwoStacks((i**2 for i in range(1, 4)))
Queue((1, 4, 9))
"""
self._stack1: list[_T] = list(iterable or [])
self._stack2: list[_T] = []

def __len__(self) -> int:
"""
>>> len(QueueByTwoStacks())
0
>>> from string import ascii_lowercase
>>> len(QueueByTwoStacks(ascii_lowercase))
26
>>> queue = QueueByTwoStacks()
>>> for i in range(1, 11):
... queue.put(i)
...
>>> len(queue)
10
>>> for i in range(2):
... queue.get()
1
2
>>> len(queue)
8
"""

return len(self._stack1) + len(self._stack2)

def __repr__(self) -> str:
"""
>>> queue = QueueByTwoStacks()
>>> queue
Queue(())
>>> str(queue)
'Queue(())'
>>> queue.put(10)
>>> queue
Queue((10,))
>>> queue.put(20)
>>> queue.put(30)
>>> queue
Queue((10, 20, 30))
"""
return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

def put(self, item: _T) -> None:
"""
Put `item` into the Queue

>>> queue = QueueByTwoStacks()
>>> queue.put(10)
>>> queue.put(20)
>>> len(queue)
2
>>> queue
Queue((10, 20))
"""

self._stack1.append(item)

def get(self) -> _T:
"""
Get `item` from the Queue

>>> queue = QueueByTwoStacks((10, 20, 30))
>>> queue.get()
10
>>> queue.put(40)
>>> queue.get()
20
>>> queue.get()
30
>>> len(queue)
1
>>> queue.get()
40
>>> queue.get()
Traceback (most recent call last):
...
IndexError: Queue is empty
"""

# To reduce number of attribute look-ups in `while` loop.
stack1_pop = self._stack1.pop
stack2_append = self._stack2.append

if not self._stack2:
while self._stack1:
stack2_append(stack1_pop())

if not self._stack2:
raise IndexError("Queue is empty")
return self._stack2.pop()


if __name__ == "__main__":
from doctest import testmod

testmod()
137 changes: 137 additions & 0 deletions data_structures/queue/queue_on_two_stacks.py
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
def __init__(self, iterable: Iterable[_T] | None = None) -> None:
"""
>>> queue1 = QueueByTwoStacks()
>>> str(queue1)
'Queue([])'
>>> queue2 = QueueByTwoStacks([10, 20, 30])
>>> str(queue2)
'Queue([10, 20, 30])'
>>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
>>> str(queue3)
'Queue([1, 4, 9])'
"""

self._stack1: list[_T] = [] if iterable is None else list(iterable)
self._stack2: list[_T] = []

def __len__(self) -> int:
"""
>>> queue = QueueByTwoStacks()
>>> for i in range(1, 11):
... queue.put(i)
...
>>> len(queue) == 10
True
>>> for i in range(2):
... queue.get()
1
2
>>> len(queue) == 8
True
"""

return len(self._stack1) + len(self._stack2)

def __repr__(self) -> str:
"""
>>> queue = QueueByTwoStacks()
>>> queue
Queue([])
>>> str(queue)
'Queue([])'
>>> queue.put(10)
>>> queue
Queue([10])
>>> queue.put(20)
>>> queue.put(30)
>>> queue
Queue([10, 20, 30])
"""

items = self._stack2[::-1] + self._stack1
return f"Queue({items})"

def put(self, item: _T) -> None:
"""
Put `item` into the Queue

>>> queue = QueueByTwoStacks()
>>> queue.put(10)
>>> queue.put(20)
>>> len(queue) == 2
True
>>> str(queue)
'Queue([10, 20])'
"""

self._stack1.append(item)

def get(self) -> _T:
"""
Get `item` from the Queue

>>> queue = QueueByTwoStacks()
>>> for i in (10, 20, 30):
... queue.put(i)
>>> queue.get()
10
>>> queue.put(40)
>>> queue.get()
20
>>> queue.get()
30
>>> len(queue) == 1
True
>>> queue.get()
40
>>> queue.get()
Traceback (most recent call last):
...
IndexError: Queue is empty
"""

# To reduce number of attribute look-ups in `while` loop.
stack1_pop = self._stack1.pop
stack2_append = self._stack2.append

if not self._stack2:
while self._stack1:
stack2_append(stack1_pop())

if not self._stack2:
raise IndexError("Queue is empty")
return self._stack2.pop()

def size(self) -> int:
"""
Returns the length of the Queue

>>> queue = QueueByTwoStacks()
>>> queue.size()
0
>>> queue.put(10)
>>> queue.put(20)
>>> queue.size()
2
>>> queue.get()
10
>>> queue.size() == 1
True
"""

return len(self)


if __name__ == "__main__":
from doctest import testmod

testmod()
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
Skip to content
Queue implementation using two Stacks#8617

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 Merged

cclauss
merged 7 commits into

from

Apr 8, 2023
 Merged


Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
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';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
Skip to content
Queue implementation using two Stacks#8617

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 Merged

cclauss
merged 7 commits into

from

Apr 8, 2023
 Merged


Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
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Queue implementation using two Stacks#8617

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cclauss
merged 7 commits into

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Apr 8, 2023
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Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
Skip to content
Queue implementation using two Stacks#8617

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 Merged

cclauss
merged 7 commits into

from

Apr 8, 2023
 Merged


Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
Skip to content
Queue implementation using two Stacks#8617

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 Merged

cclauss
merged 7 commits into

from

Apr 8, 2023
 Merged


Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
})();
Queue implementation using two Stacks by amirsoroush · Pull Request #8617 · TheAlgorithms/Python · GitHub
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 Merged

cclauss
merged 7 commits into

from

Apr 8, 2023
 Merged


Queue implementation using two Stacks
#8617
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49ce661

Queue implementation using two Stacks


amirsoroush Apr 7, 2023
37bd353

fix typo in queue/queue_on_two_stacks.py


amirsoroush Apr 7, 2023
1da0297

add 'iterable' to queue_on_two_stacks initializer


amirsoroush Apr 8, 2023
100ec02

make queue_on_two_stacks.py generic class


amirsoroush Apr 8, 2023
d9accd5

fix ruff-UP007 in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
953660b

enhance readability in queue_on_two_stacks.py


amirsoroush Apr 8, 2023
a8eb743

Create queue_by_two_stacks.py


cclauss Apr 8, 2023

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115 changes: 115 additions & 0 deletions
data_structures/queue/queue_by_two_stacks.py

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,115 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> QueueByTwoStacks()
 Queue(())
 >>> QueueByTwoStacks([10, 20, 30])
 Queue((10, 20, 30))
 >>> QueueByTwoStacks((i**2 for i in range(1, 4)))
 Queue((1, 4, 9))
 """
 self._stack1: list[_T] = list(iterable or [])
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> len(QueueByTwoStacks())
 0
 >>> from string import ascii_lowercase
 >>> len(QueueByTwoStacks(ascii_lowercase))
 26
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue)
 10
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue)
 8
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue(())
 >>> str(queue)
 'Queue(())'
 >>> queue.put(10)
 >>> queue
 Queue((10,))
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue((10, 20, 30))
 """
 return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue)
 2
 >>> queue
 Queue((10, 20))
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks((10, 20, 30))
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue)
 1
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()


if __name__ == "__main__":
 from doctest import testmod

 testmod()

137 changes: 137 additions & 0 deletions
data_structures/queue/queue_on_two_stacks.py

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,137 @@
"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")


class QueueByTwoStacks(Generic[_T]):
 def __init__(self, iterable: Iterable[_T] | None = None) -> None:
 """
 >>> queue1 = QueueByTwoStacks()
 >>> str(queue1)
 'Queue([])'
 >>> queue2 = QueueByTwoStacks([10, 20, 30])
 >>> str(queue2)
 'Queue([10, 20, 30])'
 >>> queue3 = QueueByTwoStacks((i**2 for i in range(1, 4)))
 >>> str(queue3)
 'Queue([1, 4, 9])'
 """

 self._stack1: list[_T] = [] if iterable is None else list(iterable)
 self._stack2: list[_T] = []

 def __len__(self) -> int:
 """
 >>> queue = QueueByTwoStacks()
 >>> for i in range(1, 11):
 ... queue.put(i)
 ...
 >>> len(queue) == 10
 True
 >>> for i in range(2):
 ... queue.get()
 1
 2
 >>> len(queue) == 8
 True
 """

 return len(self._stack1) + len(self._stack2)

 def __repr__(self) -> str:
 """
 >>> queue = QueueByTwoStacks()
 >>> queue
 Queue([])
 >>> str(queue)
 'Queue([])'
 >>> queue.put(10)
 >>> queue
 Queue([10])
 >>> queue.put(20)
 >>> queue.put(30)
 >>> queue
 Queue([10, 20, 30])
 """

 items = self._stack2[::-1] + self._stack1
 return f"Queue({items})"

 def put(self, item: _T) -> None:
 """
 Put `item` into the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.put(10)
 >>> queue.put(20)
 >>> len(queue) == 2
 True
 >>> str(queue)
 'Queue([10, 20])'
 """

 self._stack1.append(item)

 def get(self) -> _T:
 """
 Get `item` from the Queue

 >>> queue = QueueByTwoStacks()
 >>> for i in (10, 20, 30):
 ... queue.put(i)
 >>> queue.get()
 10
 >>> queue.put(40)
 >>> queue.get()
 20
 >>> queue.get()
 30
 >>> len(queue) == 1
 True
 >>> queue.get()
 40
 >>> queue.get()
 Traceback (most recent call last):
 ...
 IndexError: Queue is empty
 """

 # To reduce number of attribute look-ups in `while` loop.
 stack1_pop = self._stack1.pop
 stack2_append = self._stack2.append

 if not self._stack2:
 while self._stack1:
 stack2_append(stack1_pop())

 if not self._stack2:
 raise IndexError("Queue is empty")
 return self._stack2.pop()

 def size(self) -> int:
 """
 Returns the length of the Queue

 >>> queue = QueueByTwoStacks()
 >>> queue.size()
 0
 >>> queue.put(10)
 >>> queue.put(20)
 >>> queue.size()
 2
 >>> queue.get()
 10
 >>> queue.size() == 1
 True
 """

 return len(self)


if __name__ == "__main__":
 from doctest import testmod

 testmod()