LeetCode Problems

2,913 problems · Solve with AI-powered hints & explanations

#	Title	Topics	Difficulty
1	Two Sum	ArrayHash Table	Easy
2	Add Two Numbers	Linked ListMathRecursion	Medium
3	Longest Substring Without Repeating Characters	Hash TableStringSliding Window	Medium
4	Median of Two Sorted Arrays	ArrayBinary SearchDivide and Conquer	Hard
5	Longest Palindromic Substring	Two PointersStringDynamic Programming	Medium
6	Zigzag Conversion	String	Medium
7	Reverse Integer	Math	Medium
8	String to Integer (atoi)	String	Medium
9	Palindrome Number	Math	Easy
10	Regular Expression Matching	StringDynamic ProgrammingRecursion	Hard
11	Container With Most Water	ArrayTwo PointersGreedy	Medium
12	Integer to Roman	Hash TableMathString	Medium
13	Roman to Integer	Hash TableMathString	Easy
14	Longest Common Prefix	ArrayStringTrie	Easy
15	3Sum	ArrayTwo PointersSorting	Medium
16	3Sum Closest	ArrayTwo PointersSorting	Medium
17	Letter Combinations of a Phone Number	Hash TableStringBacktracking	Medium
18	4Sum	ArrayTwo PointersSorting	Medium
19	Remove Nth Node From End of List	Linked ListTwo Pointers	Medium
20	Valid Parentheses	StringStack	Easy
21	Merge Two Sorted Lists	Linked ListRecursion	Easy
22	Generate Parentheses	StringDynamic ProgrammingBacktracking	Medium
23	Merge k Sorted Lists	Linked ListDivide and ConquerHeap (Priority Queue)+1	Hard
24	Swap Nodes in Pairs	Linked ListRecursion	Medium
25	Reverse Nodes in k-Group	Linked ListRecursion	Hard
26	Remove Duplicates from Sorted Array	ArrayTwo Pointers	Easy
27	Remove Element	ArrayTwo Pointers	Easy
28	Find the Index of the First Occurrence in a String	Two PointersStringString Matching	Easy
29	Divide Two Integers	MathBit Manipulation	Medium
30	Substring with Concatenation of All Words	Hash TableStringSliding Window	Hard
31	Next Permutation	ArrayTwo Pointers	Medium
32	Longest Valid Parentheses	StringDynamic ProgrammingStack	Hard
33	Search in Rotated Sorted Array	ArrayBinary Search	Medium
34	Find First and Last Position of Element in Sorted Array	ArrayBinary Search	Medium
35	Search Insert Position	ArrayBinary Search	Easy
36	Valid Sudoku	ArrayHash TableMatrix	Medium
37	Sudoku Solver	ArrayHash TableBacktracking+1	Hard
38	Count and Say	String	Medium
39	Combination Sum	ArrayBacktracking	Medium
40	Combination Sum II	ArrayBacktracking	Medium
41	First Missing Positive	ArrayHash Table	Hard
42	Trapping Rain Water	ArrayTwo PointersDynamic Programming+2	Hard
43	Multiply Strings	MathStringSimulation	Medium
44	Wildcard Matching	StringDynamic ProgrammingGreedy+1	Hard
45	Jump Game II	ArrayDynamic ProgrammingGreedy	Medium
46	Permutations	ArrayBacktracking	Medium
47	Permutations II	ArrayBacktrackingSorting	Medium
48	Rotate Image	ArrayMathMatrix	Medium
49	Group Anagrams	ArrayHash TableString+1	Medium
50	Pow(x, n)	MathRecursion	Medium

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