429.N-ary Tree Level Order Traversal
MediumBreadth-First SearchTree71.6% acceptance3 companiesVideo
Medium · 2,078 results
430.Flatten a Multilevel Doubly Linked List
MediumDepth-First SearchDoubly-Linked ListLinked List63.3% acceptance6 companiesVideo
433.Minimum Genetic Mutation
MediumBreadth-First SearchHash TableString57.1% acceptance6 companiesVideo
435.Non-overlapping Intervals
MediumArrayDynamic ProgrammingGreedy57.5% acceptance18 companiesVideo
436.Find Right Interval
MediumArrayBinary SearchSorting56.7% acceptance4 companiesVideo
437.Path Sum III
MediumBinary TreeDepth-First SearchTree46.6% acceptance11 companiesVideo
438.Find All Anagrams in a String
MediumHash TableSliding WindowString54.7% acceptance15 companiesVideo
439.Ternary Expression Parser
MediumRecursionStackString62.6% acceptance1 companyPremium elsewhere, free hereVideo
442.Find All Duplicates in an Array
MediumArrayHash Table76.8% acceptance11 companiesVideo
443.String Compression
MediumStringTwo Pointers60.9% acceptance41 companiesVideo
444.Sequence Reconstruction
MediumArrayGraphTopological Sort31.2% acceptance2 companiesPremium elsewhere, free hereVideo
445.Add Two Numbers II
MediumLinked ListMathStack63.1% acceptance9 companiesVideo
447.Number of Boomerangs
MediumArrayHash TableMath58.0% acceptance2 companiesVideo
449.Serialize and Deserialize BST
MediumBinary Search TreeBinary TreeBreadth-First Search60.1% acceptance4 companiesVideo
450.Delete Node in a BST
MediumBinary Search TreeBinary TreeTree55.1% acceptance11 companiesVideo
451.Sort Characters By Frequency
MediumBucket SortCountingHash Table75.8% acceptance16 companiesVideo
452.Minimum Number of Arrows to Burst Balloons
MediumArrayGreedySorting61.9% acceptance8 companiesVideo
453.Minimum Moves to Equal Array Elements
MediumArrayMath59.2% acceptance8 companiesVideo
454.4Sum II
MediumArrayHash Table57.9% acceptance4 companiesVideo
456.132 Pattern
MediumArrayBinary SearchMonotonic Stack35.2% acceptance8 companiesVideo
457.Circular Array Loop
MediumArrayHash TableTwo Pointers38.3% acceptance4 companiesVideo
462.Minimum Moves to Equal Array Elements II
MediumArrayMathSorting62.2% acceptance5 companiesVideo
464.Can I Win
MediumBit ManipulationBitmaskDynamic Programming31.7% acceptance4 companiesVideo
467.Unique Substrings in Wraparound String
MediumDynamic ProgrammingString44.0% acceptance2 companiesVideo
468.Validate IP Address
MediumString28.2% acceptance12 companiesVideo
469.Convex Polygon
MediumArrayGeometryMath40.3% acceptance1 companyPremium elsewhere, free hereVideo
470.Implement Rand10() Using Rand7()
MediumMathProbability and StatisticsRandomized47.0% acceptance6 companiesVideo
473.Matchsticks to Square
MediumArrayBacktrackingBit Manipulation42.3% acceptance9 companiesVideo
474.Ones and Zeroes
MediumArrayDynamic ProgrammingString53.7% acceptance5 companiesVideo
475.Heaters
MediumArrayBinary SearchSorting42.9% acceptance12 companiesVideo
477.Total Hamming Distance
MediumArrayBit ManipulationMath55.3% acceptance3 companiesVideo
478.Generate Random Point in a Circle
MediumGeometryMathRandomized43.8% acceptance2 companiesVideo
481.Magical String
MediumStringTwo Pointers56.6% acceptance3 companiesVideo
484.Find Permutation
MediumArrayGreedyStack67.0% acceptance1 companyPremium elsewhere, free hereVideo
486.Predict the Winner
MediumArrayDynamic ProgrammingGame Theory59.7% acceptance6 companiesVideo
487.Max Consecutive Ones II
MediumArrayDynamic ProgrammingSliding Window52.0% acceptance4 companiesPremium elsewhere, free hereVideo
490.The Maze
MediumArrayBreadth-First SearchDepth-First Search60.4% acceptance13 companiesPremium elsewhere, free hereVideo
491.Non-decreasing Subsequences
MediumArrayBacktrackingBit Manipulation63.1% acceptance3 companiesVideo
494.Target Sum
MediumArrayBacktrackingDynamic Programming52.6% acceptance10 companiesVideo
497.Random Point in Non-overlapping Rectangles
MediumArrayBinary SearchMath40.8% acceptance2 companiesVideo
498.Diagonal Traverse
MediumArrayMatrixSimulation67.1% acceptance12 companiesVideo
503.Next Greater Element II
MediumArrayMonotonic StackStack69.3% acceptance16 companiesVideo
505.The Maze II
MediumArrayBreadth-First SearchDepth-First Search55.0% acceptance5 companiesPremium elsewhere, free hereVideo
508.Most Frequent Subtree Sum
MediumBinary TreeDepth-First SearchHash Table69.6% acceptance3 companiesVideo
510.Inorder Successor in BST II
MediumBinary Search TreeBinary TreeTree60.9% acceptance3 companiesPremium elsewhere, free hereVideo
513.Find Bottom Left Tree Value
MediumBinary TreeBreadth-First SearchDepth-First Search72.2% acceptance7 companiesVideo
515.Find Largest Value in Each Tree Row
MediumBinary TreeBreadth-First SearchDepth-First Search66.3% acceptance8 companiesVideo
516.Longest Palindromic Subsequence
MediumDynamic ProgrammingString65.8% acceptance15 companiesVideo
518.Coin Change II
MediumArrayDynamic Programming59.1% acceptance11 companiesVideo
519.Random Flip Matrix
MediumHash TableMathRandomized46.9% acceptance1 companyVideo
Showing 251–300 of 2,078
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.