797.All Paths From Source to Target
MediumBacktrackingBreadth-First SearchDepth-First Search83.6% acceptance5 companiesVideo
Medium · 164 results
802.Find Eventual Safe States
MediumBreadth-First SearchDepth-First SearchGraph71.6% acceptance7 companiesVideo
841.Keys and Rooms
MediumBreadth-First SearchDepth-First SearchGraph76.2% acceptance10 companiesVideo
863.All Nodes Distance K in Binary Tree
MediumBinary TreeBreadth-First SearchDepth-First Search68.1% acceptance16 companiesVideo
865.Smallest Subtree with all the Deepest Nodes
MediumBinary TreeBreadth-First SearchDepth-First Search77.5% acceptance4 companiesVideo
886.Possible Bipartition
MediumBreadth-First SearchDepth-First SearchGraph53.0% acceptance11 companiesVideo
909.Snakes and Ladders
MediumArrayBreadth-First SearchMatrix48.0% acceptance12 companiesVideo
919.Complete Binary Tree Inserter
MediumBinary TreeBreadth-First SearchDesign65.0% acceptance3 companiesVideo
934.Shortest Bridge
MediumArrayBreadth-First SearchDepth-First Search59.9% acceptance16 companiesVideo
958.Check Completeness of a Binary Tree
MediumBinary TreeBreadth-First SearchTree59.6% acceptance5 companiesVideo
959.Regions Cut By Slashes
MediumArrayBreadth-First SearchDepth-First Search77.8% acceptance6 companiesVideo
967.Numbers With Same Consecutive Differences
MediumBacktrackingBreadth-First Search59.1% acceptance5 companiesVideo
994.Rotting Oranges
MediumArrayBreadth-First SearchMatrix59.5% acceptance52 companiesVideo
1020.Number of Enclaves
MediumArrayBreadth-First SearchDepth-First Search72.2% acceptance5 companiesVideo
1034.Coloring A Border
MediumArrayBreadth-First SearchDepth-First Search51.8% acceptance3 companiesVideo
1042.Flower Planting With No Adjacent
MediumBreadth-First SearchDepth-First SearchGraph54.1% acceptance2 companiesVideo
1087.Brace Expansion
MediumBacktrackingBreadth-First SearchString66.5% acceptance6 companiesPremium elsewhere, free hereVideo
1091.Shortest Path in Binary Matrix
MediumArrayBreadth-First SearchMatrix51.8% acceptance15 companiesVideo
1102.Path With Maximum Minimum Value
MediumArrayBinary SearchBreadth-First Search54.6% acceptance3 companiesPremium elsewhere, free hereVideo
1123.Lowest Common Ancestor of Deepest Leaves
MediumBinary TreeBreadth-First SearchDepth-First Search79.5% acceptance4 companiesVideo
1129.Shortest Path with Alternating Colors
MediumBreadth-First SearchGraph48.4% acceptance5 companiesVideo
1161.Maximum Level Sum of a Binary Tree
MediumBinary TreeBreadth-First SearchDepth-First Search70.0% acceptance4 companiesVideo
1162.As Far from Land as Possible
MediumArrayBreadth-First SearchDynamic Programming52.2% acceptance7 companiesVideo
1197.Minimum Knight Moves
MediumBreadth-First Search41.8% acceptance13 companiesPremium elsewhere, free hereVideo
1202.Smallest String With Swaps
MediumArrayBreadth-First SearchDepth-First Search61.0% acceptance8 companiesVideo
1215.Stepping Numbers
MediumBacktrackingBreadth-First SearchMath48.2% acceptance1 companyPremium elsewhere, free hereVideo
1236.Web Crawler
MediumBreadth-First SearchDepth-First SearchInteractive68.8% acceptance7 companiesPremium elsewhere, free hereVideo
1245.Tree Diameter
MediumBreadth-First SearchDepth-First SearchGraph61.1% acceptance7 companiesPremium elsewhere, free hereVideo
1254.Number of Closed Islands
MediumArrayBreadth-First SearchDepth-First Search70.4% acceptance5 companiesVideo
1257.Smallest Common Region
MediumArrayBreadth-First SearchDepth-First Search68.6% acceptance1 companyPremium elsewhere, free hereVideo
1261.Find Elements in a Contaminated Binary Tree
MediumBinary TreeBreadth-First SearchDepth-First Search84.1% acceptance2 companiesVideo
1267.Count Servers that Communicate
MediumArrayBreadth-First SearchCounting73.5% acceptance6 companiesVideo
1273.Delete Tree Nodes
MediumArrayBreadth-First SearchDepth-First Search61.2% acceptance1 companyPremium elsewhere, free hereVideo
1302.Deepest Leaves Sum
MediumBinary TreeBreadth-First SearchDepth-First Search86.3% acceptance3 companiesVideo
1306.Jump Game III
MediumArrayBreadth-First SearchDepth-First Search70.1% acceptance3 companiesVideo
1311.Get Watched Videos by Your Friends
MediumArrayBreadth-First SearchGraph54.2% acceptance3 companiesVideo
1315.Sum of Nodes with Even-Valued Grandparent
MediumBinary TreeBreadth-First SearchDepth-First Search85.6% acceptance4 companiesVideo
1319.Number of Operations to Make Network Connected
MediumBreadth-First SearchDepth-First SearchGraph67.0% acceptance10 companiesVideo
1361.Validate Binary Tree Nodes
MediumBinary TreeBreadth-First SearchDepth-First Search44.3% acceptance3 companiesVideo
1376.Time Needed to Inform All Employees
MediumBreadth-First SearchDepth-First SearchTree60.6% acceptance5 companiesVideo
1391.Check if There is a Valid Path in a Grid
MediumArrayBreadth-First SearchDepth-First Search64.5% acceptance3 companiesVideo
1430.Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree
MediumBinary TreeBreadth-First SearchDepth-First Search47.6% acceptancePremium elsewhere, free hereVideo
1443.Minimum Time to Collect All Apples in a Tree
MediumBreadth-First SearchDepth-First SearchHash Table63.6% acceptance4 companiesVideo
1448.Count Good Nodes in Binary Tree
MediumBinary TreeBreadth-First SearchDepth-First Search73.8% acceptance7 companiesVideo
1457.Pseudo-Palindromic Paths in a Binary Tree
MediumBinary TreeBit ManipulationBreadth-First Search68.3% acceptance2 companiesVideo
1462.Course Schedule IV
MediumBreadth-First SearchDepth-First SearchGraph60.4% acceptance6 companiesVideo
1466.Reorder Routes to Make All Paths Lead to the City Zero
MediumBreadth-First SearchDepth-First SearchGraph66.3% acceptance5 companiesVideo
1485.Clone Binary Tree With Random Pointer
MediumBinary TreeBreadth-First SearchDepth-First Search81.2% acceptance2 companiesPremium elsewhere, free hereVideo
1490.Clone N-ary Tree
MediumBreadth-First SearchDepth-First SearchHash Table83.2% acceptance1 companyPremium elsewhere, free hereVideo
1519.Number of Nodes in the Sub-Tree With the Same Label
MediumBreadth-First SearchCountingDepth-First Search55.5% acceptance2 companiesVideo
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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.