Leetcode

• This is a Repository where I record my solutions to LeetCode Problems
• I will periodically update the README to keep the categories up-to-date
• Life is not a race, but there's no speed limit either :)
• Have FUN

Algorithms

• Arrays
• Binary Search
• Breadth First Search
• Depth First Search
• Graph
• Heap
• Linked Lists
• Math
• Recursion
• Stack
• Strings
• Trees
• Queue

Questions

#	Title	Time	Space	Difficulty	Notes	Tags
1	Two Sum	O(n)	O(n)	Easy	-	Array, HashMap
2	Add Two Numbers	O(n)	O(1)	Medium	-	LinkedList
3	Longest Substring Without Repeating Characters	O(n)	O(size(char_set))	Medium	-	HashMap
4	Median of Two Sorted Arrays	O(log(min(m,n)))	O(1)	Hard	R	Math, BinarySearch
5	Longest Palindromic Substring	O(n^2)	O(1)	Medium	-	DP, Array
6	ZigZag Conversion	O(n)	O(n)	Medium	-	String
7	Reverse Integer	O(logn (base10))	O(1)	Easy	-	Math
8	String to Integer	O(n)	O(n)	Medium	-	Math, String
9	Palindrome Number	O(logn (base10))	O(1)	Easy	-	Math
10	Regular Expression Matching
11	Container With Most Water	O(n)	O(1)	Medium	-	Array, Two Pointers
12	Integer to Roman	O(n)	O(n)	Medium	ordered processing	Math, String
13	Roman to Integer	O(n)	O(1)	Easy	clean up	Math, String
14	Longest Common Prefix	O(n*len(lcp))	O(lcp)	Easy	-	String
15	3Sum	O(n^2)	O(1)	Medium	-	Two Pointers, Arrays
16	3Sum Closest	O(n^2)	O(1)	Medium	-	Two Pointers, Arrays
17	Letter Combinations of a Phone Number	O(~3^n)	O(~3^n)	Medium	-	Backtracking
18	4Sum	O(n^3)	O(1)	Medium	-	Two Pointers
19	Remove Nth Node From End of List	O(n)	O(1)	Medium	-	Two Pointers, LinkedList
20	Valid Parentheses	O(n)	O(n)	Easy	-	String, Stack
21	Merge Two Sorted Lists	O(m+n)	O(1)	Easy	-	LinkedList
22	Generate Parentheses	O(Catalan Number)	O(1)excluding op	Medium	-	String, Backtracking
23	Merge k Sorted Lists	O(nlogk)	O(k)	Hard	Try constant space approach	LinkedList, Heap, Divide and Conquer
24	Swap Nodes in Pairs	O(n)	O(1)	Medium	-	LinkedList
25	Reverse Nodes in k-Group
26	Remove Duplicates from Sorted Array	O(n)	O(1)	Easy	in-place	Two Pointers, Arrays
27	Remove Element	O(n)	O(1)	Easy	in-place	Two Pointers, Arrays
28	Implement strStr()			Easy	using KMP	Two Pointers, String
29	Divide Two Integers	O(log(dividend))	O(1)	Medium	-	Binary Search, Math
30	Substring with Concatenation of All Words			Hard		HashMap, Two Pointers, String
Check out the Python directory for more...