Solutions & Explanations

Browse 4,029+ detailed solutions with multiple approaches, code in Python, Java, C++ and more.

4,029 Solutions961 Easy2102 Medium966 Hard

Title	Difficulty	Acceptance	Topics	Solution
2. Add Two Numbers	Medium	49.3%	Linked List Math+1	Read
3. Longest Substring Without Repeating Characters	Medium	39.9%	Hash Table Sliding Window+1	Read
5. Longest Palindromic Substring	Medium	38.7%	Dynamic Programming String+1	Read
6. Zigzag Conversion	Medium	54.9%	String	Read
7. Reverse Integer	Medium	32.2%	Math	Read
8. String to Integer (atoi)	Medium	21.4%	String	Read
11. Container With Most Water	Medium	60.9%	Array Greedy+1	Read
12. Integer to Roman	Medium	71.2%	Hash Table Math+1	Read
15. 3Sum	Medium	39.5%	Array Sorting+1	Read
16. 3Sum Closest	Medium	47.4%	Array Sorting+1	Read
17. Letter Combinations of a Phone Number	Medium	66.9%	Backtracking Hash Table+1	Read
18. 4Sum	Medium	41.4%	Array Sorting+1	Read
19. Remove Nth Node From End of List	Medium	52.4%	Linked List Two Pointers	Read
22. Generate Parentheses	Medium	79.0%	Backtracking Dynamic Programming+1	Read
24. Swap Nodes in Pairs	Medium	70.3%	Linked List Recursion	Read
29. Divide Two Integers	Medium	20.1%	Bit Manipulation Math	Read
31. Next Permutation	Medium	46.1%	Array Two Pointers	Read
33. Search in Rotated Sorted Array	Medium	45.5%	Array Binary Search	Read
34. Find First and Last Position of Element in Sorted Array	Medium	49.7%	Array Binary Search	Read
36. Valid Sudoku	Medium	64.9%	Array Hash Table+1	Read
38. Count and Say	Medium	63.7%	String	Read
39. Combination Sum	Medium	76.9%	Array Backtracking	Read
40. Combination Sum II	Medium	59.7%	Array Backtracking	Read
43. Multiply Strings	Medium	44.4%	Math Simulation+1	Read
45. Jump Game II	Medium	43.2%	Array Dynamic Programming+1	Read
46. Permutations	Medium	82.3%	Array Backtracking	Read
47. Permutations II	Medium	63.7%	Array Backtracking	Read
48. Rotate Image	Medium	80.7%	Array Math+1	Read
49. Group Anagrams	Medium	73.0%	Array Hash Table+2	Read
50. Pow(x, n)	Medium	39.0%	Math Recursion	Read
53. Maximum Subarray	Medium	53.7%	Array Divide and Conquer+1	Read
54. Spiral Matrix	Medium	57.6%	Array Matrix+1	Read
55. Jump Game	Medium	41.2%	Array Dynamic Programming+1	Read
56. Merge Intervals	Medium	52.6%	Array Sorting	Read
57. Insert Interval	Medium	45.5%	Array	Read
59. Spiral Matrix II	Medium	75.4%	Array Matrix+1	Read
61. Rotate List	Medium	43.1%	Linked List Two Pointers	Read
62. Unique Paths	Medium	67.3%	Combinatorics Dynamic Programming+1	Read
63. Unique Paths II	Medium	44.9%	Array Dynamic Programming+1	Read
64. Minimum Path Sum	Medium	68.6%	Array Dynamic Programming+1	Read
71. Simplify Path	Medium	51.4%	Stack String	Read
72. Edit Distance	Medium	60.9%	Dynamic Programming String	Read
73. Set Matrix Zeroes	Medium	63.2%	Array Hash Table+1	Read
74. Search a 2D Matrix	Medium	54.4%	Array Binary Search+1	Read
75. Sort Colors	Medium	69.9%	Array Sorting+1	Read
77. Combinations	Medium	74.9%	Backtracking	Read
78. Subsets	Medium	82.7%	Array Backtracking+1	Read
79. Word Search	Medium	48.2%	Array Backtracking+2	Read
80. Remove Duplicates from Sorted Array II	Medium	65.0%	Array Two Pointers	Read
81. Search in Rotated Sorted Array II	Medium	40.4%	Array Binary Search	Read

#2Medium

Add Two Numbers

Linked ListMathRecursion

Acceptance: 49.3%

#3Medium

Longest Substring Without Repeating Characters

Hash TableSliding WindowString

Acceptance: 39.9%

#5Medium

Longest Palindromic Substring

Dynamic ProgrammingStringTwo Pointers

Acceptance: 38.7%

#6Medium

Zigzag Conversion

String

Acceptance: 54.9%

#7Medium

Reverse Integer

Math

Acceptance: 32.2%

#8Medium

String to Integer (atoi)

String

Acceptance: 21.4%

#11Medium

Container With Most Water

ArrayGreedyTwo Pointers

Acceptance: 60.9%

#12Medium

Integer to Roman

Hash TableMathString

Acceptance: 71.2%

#15Medium

3Sum

ArraySortingTwo Pointers

Acceptance: 39.5%

#16Medium

3Sum Closest

ArraySortingTwo Pointers

Acceptance: 47.4%

#17Medium

Letter Combinations of a Phone Number

BacktrackingHash TableString

Acceptance: 66.9%

#18Medium

4Sum

ArraySortingTwo Pointers

Acceptance: 41.4%

#19Medium

Remove Nth Node From End of List

Linked ListTwo Pointers

Acceptance: 52.4%

#22Medium

Generate Parentheses

BacktrackingDynamic ProgrammingString

Acceptance: 79.0%

#24Medium

Swap Nodes in Pairs

Linked ListRecursion

Acceptance: 70.3%

#29Medium

Divide Two Integers

Bit ManipulationMath

Acceptance: 20.1%

#31Medium

Next Permutation

ArrayTwo Pointers

Acceptance: 46.1%

#33Medium

Search in Rotated Sorted Array

ArrayBinary Search

Acceptance: 45.5%

#34Medium

Find First and Last Position of Element in Sorted Array

ArrayBinary Search

Acceptance: 49.7%

#36Medium

Valid Sudoku

ArrayHash TableMatrix

Acceptance: 64.9%

#38Medium

Count and Say

String

Acceptance: 63.7%

#39Medium

Combination Sum

ArrayBacktracking

Acceptance: 76.9%

#40Medium

Combination Sum II

ArrayBacktracking

Acceptance: 59.7%

#43Medium

Multiply Strings

MathSimulationString

Acceptance: 44.4%

#45Medium

Jump Game II

ArrayDynamic ProgrammingGreedy

Acceptance: 43.2%

#46Medium

Permutations

ArrayBacktracking

Acceptance: 82.3%

#47Medium

Permutations II

ArrayBacktracking

Acceptance: 63.7%

#48Medium

Rotate Image

ArrayMathMatrix

Acceptance: 80.7%

#49Medium

Group Anagrams

ArrayHash TableSorting+1

Acceptance: 73.0%

#50Medium

Pow(x, n)

MathRecursion

Acceptance: 39.0%

#53Medium

Maximum Subarray

ArrayDivide and ConquerDynamic Programming

Acceptance: 53.7%

#54Medium

Spiral Matrix

ArrayMatrixSimulation

Acceptance: 57.6%

#55Medium

Jump Game

ArrayDynamic ProgrammingGreedy

Acceptance: 41.2%

#56Medium

Merge Intervals

ArraySorting

Acceptance: 52.6%

#57Medium

Insert Interval

Array

Acceptance: 45.5%

#59Medium

Spiral Matrix II

ArrayMatrixSimulation

Acceptance: 75.4%

#61Medium

Rotate List

Linked ListTwo Pointers

Acceptance: 43.1%

#62Medium

Unique Paths

CombinatoricsDynamic ProgrammingMath

Acceptance: 67.3%

#63Medium

Unique Paths II

ArrayDynamic ProgrammingMatrix

Acceptance: 44.9%

#64Medium

Minimum Path Sum

ArrayDynamic ProgrammingMatrix

Acceptance: 68.6%

#71Medium

Simplify Path

StackString

Acceptance: 51.4%

#72Medium

Edit Distance

Dynamic ProgrammingString

Acceptance: 60.9%

#73Medium

Set Matrix Zeroes

ArrayHash TableMatrix

Acceptance: 63.2%

#74Medium

Search a 2D Matrix

ArrayBinary SearchMatrix

Acceptance: 54.4%

#75Medium

Sort Colors

ArraySortingTwo Pointers

Acceptance: 69.9%

#77Medium

Combinations

Backtracking

Acceptance: 74.9%

#78Medium

Subsets

ArrayBacktrackingBit Manipulation

Acceptance: 82.7%

#79Medium

Word Search

ArrayBacktrackingMatrix+1

Acceptance: 48.2%

#80Medium

Remove Duplicates from Sorted Array II

ArrayTwo Pointers

Acceptance: 65.0%

#81Medium

Search in Rotated Sorted Array II

ArrayBinary Search

Acceptance: 40.4%

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