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100 questions tracked100 with solutions
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Frequency scoreSorted highest β†’ lowest frequencyβœ“ Our Solution = we have a detailed walkthrough

Showing 100 of 100 questions

1
EasyMerge Sorted Arrayβœ“ Our Solution
88
ArrayTwo PointersSorting
2
MediumPow(x, n)βœ“ Our Solution
87
MathRecursion
3
MediumSimplify Pathβœ“ Our Solution
86
StringStack
4
MediumMerge Intervalsβœ“ Our Solution
85
ArraySorting
5
84
ArrayHash Table
6
MediumNext Permutationβœ“ Our Solution
78
ArrayTwo Pointers
7
HardMerge k Sorted Listsβœ“ Our Solution
77
Linked ListDivide and ConquerHeap (Priority Queue)Merge Sort
8
77
ArrayTwo PointersSorting
9
MediumFind First and Last Position of Element in Sorted Arrayβœ“ Our Solution
72
ArrayBinary Search
10
EasyValid Parenthesesβœ“ Our Solution
71
StringStack
11
HardValid Numberβœ“ Our Solution
70
String
12
HardMinimum Window Substringβœ“ Our Solution
69
Hash TableStringSliding Window
13
EasyLongest Common Prefixβœ“ Our Solution
67
StringTrie
14
MediumAdd Two Numbersβœ“ Our Solution
65
Linked ListMathRecursion
15
MediumLetter Combinations of a Phone Numberβœ“ Our Solution
64
Hash TableStringBacktracking
16
MediumSubsetsβœ“ Our Solution
64
ArrayBacktrackingBit Manipulation
17
MediumRemove Nth Node From End of Listβœ“ Our Solution
64
Linked ListTwo Pointers
18
MediumLongest Substring Without Repeating Charactersβœ“ Our Solution
63
Hash TableStringSliding Window
19
HardTrapping Rain Waterβœ“ Our Solution
61
ArrayTwo PointersDynamic ProgrammingStack+1
20
MediumString to Integer (atoi)βœ“ Our Solution
60
String
21
MediumLongest Palindromic Substringβœ“ Our Solution
59
Two PointersStringDynamic Programming
22
EasyRemove Duplicates from Sorted Arrayβœ“ Our Solution
59
ArrayTwo Pointers
23
HardMedian of Two Sorted Arraysβœ“ Our Solution
58
ArrayBinary SearchDivide and Conquer
24
EasyPalindrome Numberβœ“ Our Solution
57
Math
25
MediumSearch in Rotated Sorted Arrayβœ“ Our Solution
57
ArrayBinary Search
26
EasyRoman to Integerβœ“ Our Solution
56
Hash TableMathString
27
EasyMerge Two Sorted Listsβœ“ Our Solution
54
Linked ListRecursion
28
MediumGroup Anagramsβœ“ Our Solution
54
ArrayHash TableStringSorting
29
MediumCount and Sayβœ“ Our Solution
53
String
30
EasyClimbing Stairsβœ“ Our Solution
53
MathDynamic ProgrammingMemoization
31
MediumMaximum Subarrayβœ“ Our Solution
52
ArrayDivide and ConquerDynamic Programming
32
MediumContainer With Most Waterβœ“ Our Solution
52
ArrayTwo PointersGreedy
33
MediumSet Matrix Zeroesβœ“ Our Solution
51
ArrayHash TableMatrix
34
MediumSort Colorsβœ“ Our Solution
51
ArrayTwo PointersSorting
35
EasyAdd Binaryβœ“ Our Solution
51
MathStringBit ManipulationSimulation
36
MediumMultiply Stringsβœ“ Our Solution
50
MathStringSimulation
37
MediumReverse Integerβœ“ Our Solution
49
Math
38
MediumWord Searchβœ“ Our Solution
48
ArrayStringBacktrackingDepth-First Search+1
39
48
ArrayMath
40
MediumGenerate Parenthesesβœ“ Our Solution
48
StringDynamic ProgrammingBacktracking
41
MediumRotate Imageβœ“ Our Solution
47
ArrayMathMatrix
42
MediumSpiral Matrixβœ“ Our Solution
47
ArrayMatrixSimulation
43
HardRegular Expression Matchingβœ“ Our Solution
46
StringDynamic ProgrammingRecursion
44
MediumInsert Intervalβœ“ Our Solution
45
Array
45
EasyFind the Index of the First Occurrence in a Stringβœ“ Our Solution
45
Two PointersStringString Matching
46
44
MathBinary Search
47
MediumSearch a 2D Matrixβœ“ Our Solution
43
ArrayBinary SearchMatrix
48
MediumBinary Tree Zigzag Level Order Traversalβœ“ Our Solution
43
TreeBreadth-First SearchBinary Tree
49
MediumDivide Two Integersβœ“ Our Solution
43
MathBit Manipulation
50
HardLargest Rectangle in Histogramβœ“ Our Solution
43
ArrayStackMonotonic Stack
51
MediumBinary Tree Level Order Traversalβœ“ Our Solution
43
TreeBreadth-First SearchBinary Tree
52
MediumRemove Duplicates from Sorted Array IIβœ“ Our Solution
42
ArrayTwo Pointers
53
MediumUnique Pathsβœ“ Our Solution
42
MathDynamic ProgrammingCombinatorics
54
EasyRemove Elementβœ“ Our Solution
42
ArrayTwo Pointers
55
MediumJump Gameβœ“ Our Solution
42
ArrayDynamic ProgrammingGreedy
56
HardText Justificationβœ“ Our Solution
41
ArrayStringSimulation
57
MediumValidate Binary Search Treeβœ“ Our Solution
41
TreeDepth-First SearchBinary Search TreeBinary Tree
58
Medium3Sum Closestβœ“ Our Solution
40
ArrayTwo PointersSorting
59
MediumDecode Waysβœ“ Our Solution
40
StringDynamic Programming
60
MediumCombination Sumβœ“ Our Solution
40
ArrayBacktracking
61
MediumSubsets IIβœ“ Our Solution
37
ArrayBacktrackingBit Manipulation
62
37
ArrayTwo PointersSorting
63
HardMaximal Rectangleβœ“ Our Solution
37
ArrayDynamic ProgrammingStackMatrix+1
64
MediumValid Sudokuβœ“ Our Solution
37
ArrayHash TableMatrix
65
MediumPermutationsβœ“ Our Solution
36
ArrayBacktracking
66
HardReverse Nodes in k-Groupβœ“ Our Solution
36
Linked ListRecursion
67
MediumZigzag Conversionβœ“ Our Solution
36
String
68
HardFirst Missing Positiveβœ“ Our Solution
35
ArrayHash Table
69
HardWildcard Matchingβœ“ Our Solution
35
StringDynamic ProgrammingGreedyRecursion
70
EasyBinary Tree Inorder Traversalβœ“ Our Solution
35
StackTreeDepth-First SearchBinary Tree
71
EasyMinimum Depth of Binary Treeβœ“ Our Solution
35
TreeDepth-First SearchBreadth-First SearchBinary Tree
72
MediumCombination Sum IIβœ“ Our Solution
35
ArrayBacktracking
73
MediumUnique Paths IIβœ“ Our Solution
35
ArrayDynamic ProgrammingMatrix
74
34
ArrayBacktracking
75
MediumConstruct Binary Tree from Preorder and Inorder Traversalβœ“ Our Solution
34
ArrayHash TableDivide and ConquerTree+1
76
EasySearch Insert Positionβœ“ Our Solution
34
ArrayBinary Search
77
MediumJump Game IIβœ“ Our Solution
34
ArrayDynamic ProgrammingGreedy
78
MediumRotate Listβœ“ Our Solution
33
Linked ListTwo Pointers
79
MediumSearch in Rotated Sorted Array IIβœ“ Our Solution
33
ArrayBinary Search
80
EasyMaximum Depth of Binary Treeβœ“ Our Solution
32
TreeDepth-First SearchBreadth-First SearchBinary Tree
81
MediumReverse Linked List IIβœ“ Our Solution
32
Linked List
82
MediumEdit Distanceβœ“ Our Solution
32
StringDynamic Programming
83
EasyLength of Last Wordβœ“ Our Solution
32
String
84
HardSudoku Solverβœ“ Our Solution
31
ArrayHash TableBacktrackingMatrix
85
EasySymmetric Treeβœ“ Our Solution
31
TreeDepth-First SearchBreadth-First SearchBinary Tree
86
MediumConvert Sorted List to Binary Search Treeβœ“ Our Solution
27
Linked ListDivide and ConquerTreeBinary Search Tree+1
87
MediumRestore IP Addressesβœ“ Our Solution
27
StringBacktracking
88
HardLongest Valid Parenthesesβœ“ Our Solution
27
StringDynamic ProgrammingStack
89
EasySame Treeβœ“ Our Solution
26
TreeDepth-First SearchBreadth-First SearchBinary Tree
90
MediumInteger to Romanβœ“ Our Solution
26
Hash TableMathString
91
MediumSwap Nodes in Pairsβœ“ Our Solution
26
Linked ListRecursion
92
MediumCombinationsβœ“ Our Solution
24
Backtracking
93
EasyConvert Sorted Array to Binary Search Treeβœ“ Our Solution
22
ArrayDivide and ConquerTreeBinary Search Tree+1
94
MediumMinimum Path Sumβœ“ Our Solution
22
ArrayDynamic ProgrammingMatrix
95
EasyBalanced Binary Treeβœ“ Our Solution
22
TreeDepth-First SearchBinary Tree
96
MediumPermutations IIβœ“ Our Solution
18
ArrayBacktrackingSorting
97
MediumUnique Binary Search Trees IIβœ“ Our Solution
16
Dynamic ProgrammingBacktrackingTreeBinary Search Tree+1
98
HardSubstring with Concatenation of All Wordsβœ“ Our Solution
16
Hash TableStringSliding Window
99
MediumSpiral Matrix IIβœ“ Our Solution
14
ArrayMatrixSimulation
100
MediumBinary Tree Level Order Traversal IIβœ“ Our Solution
8
TreeBreadth-First SearchBinary Tree