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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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, 'i'); if (__m === '*' || __re.test(location.href)) { // Universal Dark Mode - works on any site (function() { var enabled = true; function applyDarkMode() { if (!enabled) return; // Create style element if it doesn't exist var style = document.getElementById('universal-dark-mode-style'); if (!style) { style = document.createElement('style'); style.id = 'universal-dark-mode-style'; document.head.appendChild(style); } // Dark mode CSS - inverts colors but preserves images/video style.textContent = ' /* Invert everything except media */ html { filter: invert(1) hue-rotate(180deg) !important; background: #1a1a2e !important; } /* Restore images, videos, iframes, canvas */ img, video, iframe, canvas, svg, picture, [style*="background-image"] { filter: invert(1) hue-rotate(180deg) !important; } /* Preserve specific elements that should not be inverted */ .no-dark-mode, .no-dark-mode *, [data-theme="light"], [data-theme="light"], .ace_editor, .ace_editor *, .CodeMirror, .CodeMirror *, .monaco-editor, .monaco-editor *, .markdown-body pre, .markdown-body pre *, .highlight, .highlight *, pre code, pre code * { filter: none !important; } /* Fix common UI elements */ .modal, .popup, .dropdown-menu, .tooltip, .popover { filter: invert(1) hue-rotate(180deg) !important; background: #2d2d44 !important; border-color: #444 !important; } /* Scrollbars */ ::-webkit-scrollbar { background: #1a1a2e !important; } ::-webkit-scrollbar-thumb { background: #444 !important; } ::-webkit-scrollbar-thumb:hover { background: #555 !important; } /* Selection */ ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; } ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; } '; } function removeDarkMode() { var style = document.getElementById('universal-dark-mode-style'); if (style) style.remove(); } // Toggle with Alt+Shift+D document.addEventListener('keydown', function(e) { if (e.altKey && e.shiftKey && e.key === 'D') { e.preventDefault(); enabled = !enabled; if (enabled) { applyDarkMode(); console.log('[Universal Dark Mode] Enabled'); } else { removeDarkMode(); console.log('[Universal Dark Mode] Disabled'); } } }); // Apply on load applyDarkMode(); // Re-apply on dynamic content var observer = new MutationObserver(function(mutations) { if (enabled && !document.getElementById('universal-dark-mode-style')) { applyDarkMode(); } }); observer.observe(document.head, { childList: true }); console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle'); })(); } } catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); } })(); })();
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70 changes: 63 additions & 7 deletions project_euler/problem_145/sol1.py
Original file line numberDiff line numberDiff line change
Expand Up@@ -17,17 +17,17 @@
ODD_DIGITS = [1, 3, 5, 7, 9]


def reversible_numbers(
def slow_reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
>>> slow_reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
>>> slow_reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
>>> slow_reversible_numbers(3, 0, [0] * 3, 3)
100
"""
if remaining_length == 0:
Expand All@@ -51,7 +51,7 @@ def reversible_numbers(
result = 0
for digit in range(10):
digits[length // 2] = digit
result += reversible_numbers(
result += slow_reversible_numbers(
0, (remainder + 2 * digit) // 10, digits, length
)
return result
Expand All@@ -67,7 +67,7 @@ def reversible_numbers(

for digit2 in other_parity_digits:
digits[(length - remaining_length) // 2] = digit2
result += reversible_numbers(
result += slow_reversible_numbers(
remaining_length - 2,
(remainder + digit1 + digit2) // 10,
digits,
Expand All@@ -76,6 +76,42 @@ def reversible_numbers(
return result


def slow_solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
>>> slow_solution(3)
120
>>> slow_solution(6)
18720
>>> slow_solution(7)
68720
"""
result = 0
for length in range(1, max_power + 1):
result += slow_reversible_numbers(length, 0, [0] * length, length)
return result


def reversible_numbers(
remaining_length: int, remainder: int, digits: list[int], length: int
) -> int:
"""
Count the number of reversible numbers of given length.
Iterate over possible digits considering parity of current sum remainder.
>>> reversible_numbers(1, 0, [0], 1)
0
>>> reversible_numbers(2, 0, [0] * 2, 2)
20
>>> reversible_numbers(3, 0, [0] * 3, 3)
100
"""
# There exist no reversible 1, 5, 9, 13 (ie. 4k+1) digit numbers
if (length - 1) % 4 == 0:
return 0

return slow_reversible_numbers(length, 0, [0] * length, length)


def solution(max_power: int = 9) -> int:
"""
To evaluate the solution, use solution()
Expand All@@ -92,5 +128,25 @@ def solution(max_power: int = 9) -> int:
return result


def benchmark() -> None:
"""
Benchmarks
"""
# Running performance benchmarks...
# slow_solution : 292.9300301000003
# solution : 54.90970860000016

from timeit import timeit

print("Running performance benchmarks...")

print(f"slow_solution : {timeit('slow_solution()', globals=globals(), number=10)}")
print(f"solution : {timeit('solution()', globals=globals(), number=10)}")


if __name__ == "__main__":
print(f"{solution() = }")
print(f"Solution : {solution()}")
benchmark()

# for i in range(1, 15):
# print(f"{i}. {reversible_numbers(i, 0, [0]*i, i)}")
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