51.N-Queens
HardArrayBacktracking76.3% acceptance16 companiesVideo
With video · 3,856 results
52.N-Queens II
HardBacktracking79.5% acceptance10 companiesVideo
53.Maximum Subarray
MediumArrayDivide and ConquerDynamic Programming53.7% acceptance64 companiesVideo
54.Spiral Matrix
MediumArrayMatrixSimulation58.2% acceptance49 companiesVideo
55.Jump Game
MediumArrayDynamic ProgrammingGreedy41.2% acceptance33 companiesVideo
56.Merge Intervals
MediumArraySorting52.6% acceptance112 companiesVideo
57.Insert Interval
MediumArray46.1% acceptance16 companiesVideo
58.Length of Last Word
EasyString59.7% acceptance7 companiesVideo
59.Spiral Matrix II
MediumArrayMatrixSimulation76.0% acceptance11 companiesVideo
60.Permutation Sequence
HardMathRecursion54.3% acceptance7 companiesVideo
61.Rotate List
MediumLinked ListTwo Pointers43.1% acceptance9 companiesVideo
62.Unique Paths
MediumCombinatoricsDynamic ProgrammingMath67.3% acceptance21 companiesVideo
63.Unique Paths II
MediumArrayDynamic ProgrammingMatrix44.9% acceptance9 companiesVideo
64.Minimum Path Sum
MediumArrayDynamic ProgrammingMatrix68.6% acceptance17 companiesVideo
65.Valid Number
HardString23.3% acceptance7 companiesVideo
66.Plus One
EasyArrayMath50.3% acceptance13 companiesVideo
67.Add Binary
EasyBit ManipulationMathSimulation58.4% acceptance17 companiesVideo
68.Text Justification
HardArraySimulationString52.4% acceptance44 companiesVideo
69.Sqrt(x)
EasyBinary SearchMath42.2% acceptance17 companiesVideo
70.Climbing Stairs
EasyDynamic ProgrammingMathMemoization54.0% acceptance37 companiesVideo
71.Simplify Path
MediumStackString51.4% acceptance24 companiesVideo
72.Edit Distance
MediumDynamic ProgrammingString61.5% acceptance24 companiesVideo
73.Set Matrix Zeroes
MediumArrayHash TableMatrix63.8% acceptance22 companiesVideo
74.Search a 2D Matrix
MediumArrayBinary SearchMatrix54.4% acceptance19 companiesVideo
75.Sort Colors
MediumArraySortingTwo Pointers69.9% acceptance37 companiesVideo
76.Minimum Window Substring
HardHash TableSliding WindowString48.3% acceptance35 companiesVideo
77.Combinations
MediumBacktracking74.9% acceptance8 companiesVideo
78.Subsets
MediumArrayBacktrackingBit Manipulation82.7% acceptance21 companiesVideo
79.Word Search
MediumArrayBacktrackingMatrix48.2% acceptance36 companiesVideo
80.Remove Duplicates from Sorted Array II
MediumArrayTwo Pointers65.0% acceptance9 companiesVideo
81.Search in Rotated Sorted Array II
MediumArrayBinary Search40.4% acceptance10 companiesVideo
82.Remove Duplicates from Sorted List II
MediumLinked ListTwo Pointers52.8% acceptance11 companiesVideo
83.Remove Duplicates from Sorted List
EasyLinked List57.6% acceptance9 companiesVideo
84.Largest Rectangle in Histogram
HardArrayMonotonic StackStack50.7% acceptance30 companiesVideo
85.Maximal Rectangle
HardArrayDynamic ProgrammingMatrix60.1% acceptance15 companiesVideo
86.Partition List
MediumLinked ListTwo Pointers62.0% acceptance5 companiesVideo
87.Scramble String
HardDynamic ProgrammingString45.9% acceptance6 companiesVideo
88.Merge Sorted Array
EasyArraySortingTwo Pointers55.7% acceptance37 companiesVideo
89.Gray Code
MediumBacktrackingBit ManipulationMath66.2% acceptance5 companiesVideo
90.Subsets II
MediumArrayBacktrackingBit Manipulation61.7% acceptance9 companiesVideo
91.Decode Ways
MediumDynamic ProgrammingString38.3% acceptance22 companiesVideo
92.Reverse Linked List II
MediumLinked List52.4% acceptance16 companiesVideo
93.Restore IP Addresses
MediumBacktrackingString57.3% acceptance20 companiesVideo
94.Binary Tree Inorder Traversal
EasyBinary TreeDepth-First SearchStack80.4% acceptance7 companiesVideo
95.Unique Binary Search Trees II
MediumBacktrackingBinary Search TreeBinary Tree63.3% acceptance5 companiesVideo
96.Unique Binary Search Trees
MediumBinary Search TreeBinary TreeDynamic Programming64.0% acceptance10 companiesVideo
97.Interleaving String
MediumDynamic ProgrammingString45.0% acceptance10 companiesVideo
98.Validate Binary Search Tree
MediumBinary Search TreeBinary TreeDepth-First Search36.1% acceptance18 companiesVideo
99.Recover Binary Search Tree
MediumBinary Search TreeBinary TreeDepth-First Search60.9% acceptance8 companiesVideo
100.Same Tree
EasyBinary TreeBreadth-First SearchDepth-First Search68.0% acceptance9 companiesVideo
Showing 51–100 of 3,856
How to use these solutions
Each solution breaks the problem into approaches, usually from brute force to the best one, and explains why each works. Code comes in Python, Java, C++ and other languages. Knowing why an approach works matters more in an interview than remembering the code.
- Try the problem first. Give it at least 20 minutes before you open the solution.
- Read every approach. The brute force shows you the problem; the faster ones show the pattern.
- Check the complexity. Note the time and space of each approach and what makes the difference.
- Write it yourself. Close the solution and code it from memory in the editor.
- Come back in a week. Solving it again later is what makes the pattern stick.