Binary Tree Interview Questions

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

Rank

#124HardFrequency: 90.2%

Binary Tree Maximum Path Sum

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

Rank

#1790MediumFrequency: 88.5%

Lowest Common Ancestor of a Binary Tree III

Hash Table Two Pointers Tree Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#543EasyFrequency: 86.8%

Diameter of Binary Tree

Rank

#236MediumFrequency: 86.4%

Lowest Common Ancestor of a Binary Tree

Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#199MediumFrequency: 85.4%

Binary Tree Right Side View

Tree Depth-First Search Breadth-First Search Binary Tree

Rank

#2217MediumFrequency: 83.7%

Step-By-Step Directions From a Binary Tree Node to Another

String Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#230MediumFrequency: 82.3%

Kth Smallest Element in a BST

Tree Depth-First Search Binary Search Tree Binary Tree

Rank

#129MediumFrequency: 78.4%

Sum Root to Leaf Numbers

Rank

#975EasyFrequency: 78%

Range Sum of BST

Tree Depth-First Search Binary Search Tree Binary Tree

#10

Rank

#366MediumFrequency: 76.7%

Find Leaves of Binary Tree

#11

Rank

#156MediumFrequency: 70.9%

Binary Tree Upside Down

#12

Rank

#1029HardFrequency: 69.1%

Vertical Order Traversal of a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

#13

Rank

#235MediumFrequency: 66.5%

Lowest Common Ancestor of a Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree Binary Lifting Lowest Common Ancestor

#14

Rank

#893MediumFrequency: 65.7%

All Nodes Distance K in Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#15

Rank

#108EasyFrequency: 65.5%

Convert Sorted Array to Binary Search Tree

Asked at Airbnb

Array Divide and Conquer Tree Binary Search Tree Binary Tree

#16

Rank

#104EasyFrequency: 65%

Maximum Depth of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#17

Rank

#758MediumFrequency: 63.7%

Convert Binary Search Tree to Sorted Doubly Linked List

Linked List Stack Tree Depth-First Search Binary Search Tree Binary Tree Doubly-Linked List

#18

Rank

#101EasyFrequency: 63.4%

Symmetric Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#19

Rank

#297HardFrequency: 63.4%

Serialize and Deserialize Binary Tree

String Tree Depth-First Search Breadth-First Search Design Binary Tree

#20

Rank

#2584MediumFrequency: 62.5%

Number of Nodes With Value One

Asked at Infosys

Array Tree Depth-First Search Breadth-First Search Binary Tree

#21

Rank

#270EasyFrequency: 61.8%

Closest Binary Search Tree Value

Binary Search Tree Depth-First Search Binary Search Tree Binary Tree

#22

Rank

#272HardFrequency: 61.6%

Closest Binary Search Tree Value II

Two Pointers Stack Tree Depth-First Search Binary Search Tree Heap (Priority Queue)Binary Tree

#23

Rank

#743MediumFrequency: 61.1%

Closest Leaf in a Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#24

Rank

#173MediumFrequency: 60.9%

Binary Search Tree Iterator

Stack Tree Design Binary Search Tree Binary Tree Iterator

#25

Rank

#671EasyFrequency: 60.7%

Second Minimum Node In a Binary Tree

#26

Rank

#2175MediumFrequency: 59.9%

Count Nodes With the Highest Score

Array Tree Depth-First Search Binary Tree DP on Trees

#27

Rank

#105MediumFrequency: 59.3%

Construct Binary Tree from Preorder and Inorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#28

Rank

#103MediumFrequency: 55.5%

Binary Tree Zigzag Level Order Traversal

#29

Rank

#102MediumFrequency: 54.4%

Binary Tree Level Order Traversal

#30

Rank

#998MediumFrequency: 54.4%

Check Completeness of a Binary Tree

#31

Rank

#450MediumFrequency: 53.4%

Delete Node in a BST

#32

Rank

#2461MediumFrequency: 52.9%

Amount of Time for Binary Tree to Be Infected

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#33

Rank

#662MediumFrequency: 52.9%

Maximum Width of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#34

Rank

#98MediumFrequency: 52.8%

Validate Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#35

Rank

#2347MediumFrequency: 52.7%

Count Nodes Equal to Average of Subtree

#36

Rank

#337MediumFrequency: 52.1%

House Robber III

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#37

Rank

#1780MediumFrequency: 50.6%

Lowest Common Ancestor of a Binary Tree II

Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#38

Rank

#110EasyFrequency: 50%

Balanced Binary Tree

#39

Rank

#545MediumFrequency: 49.3%

Boundary of Binary Tree

#40

Rank

#116MediumFrequency: 48.8%

Populating Next Right Pointers in Each Node

Linked List Tree Depth-First Search Breadth-First Search Binary Tree

#41

Rank

#617EasyFrequency: 48.8%

Merge Two Binary Trees

Tree Depth-First Search Breadth-First Search Binary Tree

#42

Rank

#257EasyFrequency: 48.7%

Binary Tree Paths

Asked at Apple

String Backtracking Tree Depth-First Search Binary Tree

#43

Rank

#100EasyFrequency: 48.1%

Same Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#44

Rank

#536MediumFrequency: 47.5%

Construct Binary Tree from String

String Stack Tree Depth-First Search Binary Tree

#45

Rank

#2306MediumFrequency: 47.5%

Create Binary Tree From Descriptions

Array Hash Table Tree Binary Tree

#46

Rank

#515MediumFrequency: 44.7%

Find Largest Value in Each Tree Row

Tree Depth-First Search Breadth-First Search Binary Tree

#47

Rank

#94EasyFrequency: 44.2%

Binary Tree Inorder Traversal

#48

Rank

#298MediumFrequency: 44%

Binary Tree Longest Consecutive Sequence

#49

Rank

#113MediumFrequency: 43.2%

Path Sum II

Backtracking Tree Depth-First Search Binary Tree

#50

Rank

#226EasyFrequency: 43%

Invert Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#51

Rank

#255MediumFrequency: 41.2%

Verify Preorder Sequence in Binary Search Tree

Array Stack Tree Binary Search Tree Recursion Monotonic Stack Binary Tree

#52

Rank

#789EasyFrequency: 40.8%

Kth Largest Element in a Stream

Tree Design Binary Search Tree Heap (Priority Queue)Binary Tree Data Stream

#53

Rank

#112EasyFrequency: 40.5%

Path Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#54

Rank

#114MediumFrequency: 40.5%

Flatten Binary Tree to Linked List

Linked List Stack Tree Depth-First Search Binary Tree

#55

Rank

#1207MediumFrequency: 40.2%

Delete Nodes And Return Forest

Array Hash Table Tree Depth-First Search Binary Tree

#56

Rank

#117MediumFrequency: 40%

Populating Next Right Pointers in Each Node II

Linked List Tree Depth-First Search Breadth-First Search Binary Tree

#57

Rank

#99MediumFrequency: 39.4%

Recover Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#58

Rank

#1653MediumFrequency: 39.1%

Number of Good Leaf Nodes Pairs

#59

Rank

#2780MediumFrequency: 39.1%

Make Costs of Paths Equal in a Binary Tree

Array Dynamic Programming Greedy Tree Binary Tree

#60

Rank

#437MediumFrequency: 39.1%

Path Sum III

#61

Rank

#896MediumFrequency: 38.5%

Smallest Subtree with all the Deepest Nodes

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor DP on Trees

#62

Rank

#106MediumFrequency: 38.2%

Construct Binary Tree from Inorder and Postorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#63

Rank

#1050MediumFrequency: 37.4%

Construct Binary Search Tree from Preorder Traversal

Array Stack Tree Binary Search Tree Monotonic Stack Binary Tree

#64

Rank

#96MediumFrequency: 36.8%

Unique Binary Search Trees

Math Dynamic Programming Tree Binary Search Tree Binary Tree

#65

Rank

#653EasyFrequency: 35.7%

Two Sum IV - Input is a BST

Hash Table Two Pointers Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#66

Rank

#1544MediumFrequency: 35.7%

Count Good Nodes in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#67

Rank

#930MediumFrequency: 35.6%

All Possible Full Binary Trees

Dynamic Programming Tree Recursion Memoization Binary Tree

#68

Rank

#1008HardFrequency: 35.1%

Binary Tree Cameras

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#69

Rank

#1475HardFrequency: 35.1%

Maximum Sum BST in Binary Tree

Dynamic Programming Tree Depth-First Search Binary Search Tree Binary Tree DP on Trees

#70

Rank

#1218MediumFrequency: 34%

Lowest Common Ancestor of Deepest Leaves

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor DP on Trees

#71

Rank

#1254MediumFrequency: 33%

Deepest Leaves Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#72

Rank

#572EasyFrequency: 31.9%

Subtree of Another Tree

Tree Depth-First Search String Matching Binary Tree Hash Function

#73

Rank

#1114MediumFrequency: 31.3%

Binary Search Tree to Greater Sum Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#74

Rank

#2545HardFrequency: 31.1%

Height of Binary Tree After Subtree Removal Queries

Array Tree Depth-First Search Breadth-First Search Binary Tree

#75

Rank

#1465MediumFrequency: 31.1%

Maximum Product of Splitted Binary Tree

#76

Rank

#652MediumFrequency: 30.4%

Find Duplicate Subtrees

Hash Table Tree Depth-First Search Binary Tree

#77

Rank

#513MediumFrequency: 29.3%

Find Bottom Left Tree Value

Tree Depth-First Search Breadth-First Search Binary Tree

#78

Rank

#784MediumFrequency: 29.3%

Insert into a Binary Search Tree

#79

Rank

#2646MediumFrequency: 29.1%

Kth Largest Sum in a Binary Tree

Tree Breadth-First Search Sorting Binary Tree

#80

Rank

#530EasyFrequency: 28.9%

Minimum Absolute Difference in BST

Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#81

Rank

#1116MediumFrequency: 28.1%

Maximum Level Sum of a Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#82

Rank

#95MediumFrequency: 28.1%

Unique Binary Search Trees II

Dynamic Programming Backtracking Tree Binary Search Tree Binary Tree

#83

Rank

#404EasyFrequency: 28.1%

Sum of Left Leaves

Tree Depth-First Search Breadth-First Search Binary Tree

#84

Rank

#1093HardFrequency: 27.8%

Recover a Tree From Preorder Traversal

#85

Rank

#1285MediumFrequency: 27.8%

Balance a Binary Search Tree

Divide and Conquer Greedy Tree Depth-First Search Binary Search Tree Binary Tree

#86

Rank

#1768MediumFrequency: 27.8%

Design an Expression Tree With Evaluate Function

Array Math Stack Tree Design Binary Tree

#87

Rank

#109MediumFrequency: 27.7%

Convert Sorted List to Binary Search Tree

Linked List Divide and Conquer Tree Binary Search Tree Binary Tree

#88

Rank

#285MediumFrequency: 27.3%

Inorder Successor in BST

Tree Depth-First Search Binary Search Tree Binary Tree

#89

Rank

#333MediumFrequency: 27.3%

Largest BST Subtree

Dynamic Programming Tree Depth-First Search Binary Search Tree Binary Tree DP on Trees

#90

Rank

#654MediumFrequency: 27.3%

Maximum Binary Tree

Array Divide and Conquer Stack Tree Monotonic Stack Binary Tree Cartesian Tree

#91

Rank

#1609EasyFrequency: 27.3%

Find All The Lonely Nodes

Tree Depth-First Search Breadth-First Search Binary Tree

#92

Rank

#3467MediumFrequency: 27.3%

Find the Level of Tree with Minimum Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#93

Rank

#144EasyFrequency: 27.2%

Binary Tree Preorder Traversal

#94

Rank

#222MediumFrequency: 27.2%

Count Complete Tree Nodes

Binary Search Bit Manipulation Tree Binary Tree

#95

Rank

#1498EasyFrequency: 26.7%

Find a Corresponding Node of a Binary Tree in a Clone of That Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#96

Rank

#508MediumFrequency: 26.5%

Most Frequent Subtree Sum

Hash Table Tree Depth-First Search Binary Tree DP on Trees

#97

Rank

#1092MediumFrequency: 26.5%

Maximum Difference Between Node and Ancestor

#98

Rank

#1624MediumFrequency: 26.5%

Clone Binary Tree With Random Pointer

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#99

Rank

#1816MediumFrequency: 26.5%

Lowest Common Ancestor of a Binary Tree IV

Hash Table Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#100

Rank

#2677MediumFrequency: 26.5%

Cousins in Binary Tree II

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#101

Rank

#501EasyFrequency: 25.4%

Find Mode in Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#102

Rank

#783EasyFrequency: 25.4%

Search in a Binary Search Tree

#103

Rank

#107MediumFrequency: 25.3%

Binary Tree Level Order Traversal II

#104

Rank

#449MediumFrequency: 25.1%

Serialize and Deserialize BST

String Tree Depth-First Search Breadth-First Search Design Binary Search Tree Binary Tree

#105

Rank

#538MediumFrequency: 25.1%

Convert BST to Greater Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#106

Rank

#1079EasyFrequency: 25.1%

Sum of Root To Leaf Binary Numbers

#107

Rank

#1243MediumFrequency: 25.1%

Sum of Nodes with Even-Valued Grandparent

Tree Depth-First Search Breadth-First Search Binary Tree

#108

Rank

#2558MediumFrequency: 25.1%

Minimum Number of Operations to Sort a Binary Tree by Level

#109

Rank

#637EasyFrequency: 25.1%

Average of Levels in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#110

Rank

#1275MediumFrequency: 25.1%

Validate Binary Tree Nodes

Tree Depth-First Search Breadth-First Search Union-Find Graph Theory Binary Tree

#111

Rank

#1729MediumFrequency: 25.1%

Binary Search Tree Iterator II

Stack Tree Design Binary Search Tree Binary Tree Iterator

#112

Rank

#111EasyFrequency: 25%

Minimum Depth of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#113

Rank

#925MediumFrequency: 24.4%

Construct Binary Tree from Preorder and Postorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#114

Rank

#1150MediumFrequency: 23.6%

Two Sum BSTs

Two Pointers Binary Search Stack Tree Depth-First Search Binary Search Tree Binary Tree

#115

Rank

#1427MediumFrequency: 23.6%

All Elements in Two Binary Search Trees

Tree Depth-First Search Binary Search Tree Sorting Binary Tree

#116

Rank

#1883MediumFrequency: 23.6%

Find Distance in a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#117

Rank

#1040MediumFrequency: 23.4%

Maximum Binary Tree II

#118

Rank

#509MediumFrequency: 23.4%

Inorder Successor in BST II

#119

Rank

#988MediumFrequency: 23.3%

Flip Equivalent Binary Trees

#120

Rank

#1030MediumFrequency: 23.3%

Smallest String Starting From Leaf

String Backtracking Tree Depth-First Search Binary Tree

#121

Rank

#606MediumFrequency: 21.9%

Construct String from Binary Tree

#122

Rank

#1021MediumFrequency: 21.9%

Distribute Coins in Binary Tree

#123

Rank

#1157MediumFrequency: 21.9%

Insufficient Nodes in Root to Leaf Paths

#124

Rank

#1450MediumFrequency: 21.9%

Delete Leaves With a Given Value

#125

Rank

#2126MediumFrequency: 21.5%

Count Nodes Equal to Sum of Descendants

#126

Rank

#1731MediumFrequency: 21.5%

Even Odd Tree

#127

Rank

#145EasyFrequency: 20.9%

Binary Tree Postorder Traversal

#128

Rank

#331MediumFrequency: 20.9%

Verify Preorder Serialization of a Binary Tree

#129

Rank

#2567MediumFrequency: 20.9%

Closest Nodes Queries in a Binary Search Tree

Array Binary Search Tree Depth-First Search Binary Search Tree Binary Tree

#130

Rank

#2416EasyFrequency: 20.9%

Evaluate Boolean Binary Tree

#131

Rank

#549MediumFrequency: 20.3%

Binary Tree Longest Consecutive Sequence II

#132

Rank

#663MediumFrequency: 20%

Equal Tree Partition

#133

Rank

#791MediumFrequency: 20%

Split BST

Tree Binary Search Tree Recursion Binary Tree

#134

Rank

#1091MediumFrequency: 20%

Maximum Average Subtree

#135

Rank

#1568MediumFrequency: 20%

Pseudo-Palindromic Paths in a Binary Tree

Bit Manipulation Tree Depth-First Search Breadth-First Search Binary Tree

#136

Rank

#1736HardFrequency: 20%

Build Binary Expression Tree From Infix Expression

#137

Rank

#799EasyFrequency: 19.5%

Minimum Distance Between BST Nodes

Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#138

Rank

#2384EasyFrequency: 19.5%

Root Equals Sum of Children

#139

Rank

#832MediumFrequency: 19.4%

Binary Tree Pruning

#140

Rank

#1692HardFrequency: 18%

Number of Ways to Reorder Array to Get Same BST

Array Math Divide and Conquer Dynamic Programming Tree Union-Find Binary Search Tree Memoization Combinatorics Binary Tree Fermat's Little Theorem

#141

Rank

#669MediumFrequency: 18%

Trim a Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#142

Rank

#687MediumFrequency: 16.4%

Longest Univalue Path

#143

Rank

#955MediumFrequency: 16.4%

Complete Binary Tree Inserter

Tree Breadth-First Search Design Binary Tree

#144

Rank

#1248MediumFrequency: 16.4%

Binary Tree Coloring Game

#145

Rank

#1387MediumFrequency: 16.4%

Find Elements in a Contaminated Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Design Binary Tree

#146

Rank

#1745MediumFrequency: 16.4%

Find Nearest Right Node in Binary Tree

#147

Rank

#1750MediumFrequency: 16.4%

Check If Two Expression Trees are Equivalent

Hash Table Tree Depth-First Search Binary Tree Counting

#148

Rank

#1796MediumFrequency: 16.4%

Correct a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#149

Rank

#1810MediumFrequency: 16.4%

Change the Root of a Binary Tree

#150

Rank

#2399HardFrequency: 16.4%

Minimum Flips in Binary Tree to Get Result

Dynamic Programming Tree Depth-First Search Binary Tree

#151

Rank

#2843EasyFrequency: 16.4%

Extract Kth Character From The Rope Tree

#152

Rank

#1035EasyFrequency: 15.7%

Cousins in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#153

Rank

#904EasyFrequency: 14.4%

Leaf-Similar Trees

#154

Rank

#655MediumFrequency: 12.6%

Print Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#155

Rank

#2493MediumFrequency: 12.6%

Reverse Odd Levels of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#156

Rank

#2060HardFrequency: 12%

Merge BSTs to Create Single BST

Array Hash Table Tree Depth-First Search Binary Search Tree Binary Tree

#157

Rank

#933EasyFrequency: 10.5%

Increasing Order Search Tree

Stack Tree Depth-First Search Binary Search Tree Binary Tree

#158

Rank

#1005EasyFrequency: 10.5%

Univalued Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#159

Rank

#250MediumFrequency: 10.3%

Count Univalue Subtrees

#160

Rank

#1484MediumFrequency: 8%

Linked List in Binary Tree

Linked List Tree Depth-First Search Binary Tree

#161

Rank

#1474MediumFrequency: 7.3%

Longest ZigZag Path in a Binary Tree

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#162

Rank

#563EasyFrequency: 7.2%

Binary Tree Tilt

#163

Rank

#3509MediumFrequency: 5.5%

K-th Largest Perfect Subtree Size in Binary Tree

Tree Depth-First Search Sorting Binary Tree

#164

Rank

#623MediumFrequency: 5%

Add One Row to Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#165

Rank

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Binary Tree Interview Questions

Master 165 binary tree problems frequently asked in technical interviews. These questions test your understanding of binary treeconcepts and are essential for coding interview success.

165

Total Problems

Easy

116

Medium

Hard

Binary Tree Vertical Order Traversal

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

Rank

#124HardFrequency: 90.2%

Binary Tree Maximum Path Sum

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

Rank

#1790MediumFrequency: 88.5%

Lowest Common Ancestor of a Binary Tree III

Hash Table Two Pointers Tree Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#543EasyFrequency: 86.8%

Diameter of Binary Tree

Rank

#236MediumFrequency: 86.4%

Lowest Common Ancestor of a Binary Tree

Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#199MediumFrequency: 85.4%

Binary Tree Right Side View

Tree Depth-First Search Breadth-First Search Binary Tree

Rank

#2217MediumFrequency: 83.7%

Step-By-Step Directions From a Binary Tree Node to Another

String Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

Rank

#230MediumFrequency: 82.3%

Kth Smallest Element in a BST

Tree Depth-First Search Binary Search Tree Binary Tree

Rank

#129MediumFrequency: 78.4%

Sum Root to Leaf Numbers

Rank

#975EasyFrequency: 78%

Range Sum of BST

Tree Depth-First Search Binary Search Tree Binary Tree

#10

Rank

#366MediumFrequency: 76.7%

Find Leaves of Binary Tree

#11

Rank

#156MediumFrequency: 70.9%

Binary Tree Upside Down

#12

Rank

#1029HardFrequency: 69.1%

Vertical Order Traversal of a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

#13

Rank

#235MediumFrequency: 66.5%

Lowest Common Ancestor of a Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree Binary Lifting Lowest Common Ancestor

#14

Rank

#893MediumFrequency: 65.7%

All Nodes Distance K in Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#15

Rank

#108EasyFrequency: 65.5%

Convert Sorted Array to Binary Search Tree

Asked at Airbnb

Array Divide and Conquer Tree Binary Search Tree Binary Tree

#16

Rank

#104EasyFrequency: 65%

Maximum Depth of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#17

Rank

#758MediumFrequency: 63.7%

Convert Binary Search Tree to Sorted Doubly Linked List

Linked List Stack Tree Depth-First Search Binary Search Tree Binary Tree Doubly-Linked List

#18

Rank

#101EasyFrequency: 63.4%

Symmetric Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#19

Rank

#297HardFrequency: 63.4%

Serialize and Deserialize Binary Tree

String Tree Depth-First Search Breadth-First Search Design Binary Tree

#20

Rank

#2584MediumFrequency: 62.5%

Number of Nodes With Value One

Asked at Infosys

Array Tree Depth-First Search Breadth-First Search Binary Tree

#21

Rank

#270EasyFrequency: 61.8%

Closest Binary Search Tree Value

Binary Search Tree Depth-First Search Binary Search Tree Binary Tree

#22

Rank

#272HardFrequency: 61.6%

Closest Binary Search Tree Value II

Two Pointers Stack Tree Depth-First Search Binary Search Tree Heap (Priority Queue)Binary Tree

#23

Rank

#743MediumFrequency: 61.1%

Closest Leaf in a Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#24

Rank

#173MediumFrequency: 60.9%

Binary Search Tree Iterator

Stack Tree Design Binary Search Tree Binary Tree Iterator

#25

Rank

#671EasyFrequency: 60.7%

Second Minimum Node In a Binary Tree

#26

Rank

#2175MediumFrequency: 59.9%

Count Nodes With the Highest Score

Array Tree Depth-First Search Binary Tree DP on Trees

#27

Rank

#105MediumFrequency: 59.3%

Construct Binary Tree from Preorder and Inorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#28

Rank

#103MediumFrequency: 55.5%

Binary Tree Zigzag Level Order Traversal

#29

Rank

#102MediumFrequency: 54.4%

Binary Tree Level Order Traversal

#30

Rank

#998MediumFrequency: 54.4%

Check Completeness of a Binary Tree

#31

Rank

#450MediumFrequency: 53.4%

Delete Node in a BST

#32

Rank

#2461MediumFrequency: 52.9%

Amount of Time for Binary Tree to Be Infected

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#33

Rank

#662MediumFrequency: 52.9%

Maximum Width of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#34

Rank

#98MediumFrequency: 52.8%

Validate Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#35

Rank

#2347MediumFrequency: 52.7%

Count Nodes Equal to Average of Subtree

#36

Rank

#337MediumFrequency: 52.1%

House Robber III

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#37

Rank

#1780MediumFrequency: 50.6%

Lowest Common Ancestor of a Binary Tree II

Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#38

Rank

#110EasyFrequency: 50%

Balanced Binary Tree

#39

Rank

#545MediumFrequency: 49.3%

Boundary of Binary Tree

#40

Rank

#116MediumFrequency: 48.8%

Populating Next Right Pointers in Each Node

Linked List Tree Depth-First Search Breadth-First Search Binary Tree

#41

Rank

#617EasyFrequency: 48.8%

Merge Two Binary Trees

Tree Depth-First Search Breadth-First Search Binary Tree

#42

Rank

#257EasyFrequency: 48.7%

Binary Tree Paths

Asked at Apple

String Backtracking Tree Depth-First Search Binary Tree

#43

Rank

#100EasyFrequency: 48.1%

Same Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#44

Rank

#536MediumFrequency: 47.5%

Construct Binary Tree from String

String Stack Tree Depth-First Search Binary Tree

#45

Rank

#2306MediumFrequency: 47.5%

Create Binary Tree From Descriptions

Array Hash Table Tree Binary Tree

#46

Rank

#515MediumFrequency: 44.7%

Find Largest Value in Each Tree Row

Tree Depth-First Search Breadth-First Search Binary Tree

#47

Rank

#94EasyFrequency: 44.2%

Binary Tree Inorder Traversal

#48

Rank

#298MediumFrequency: 44%

Binary Tree Longest Consecutive Sequence

#49

Rank

#113MediumFrequency: 43.2%

Path Sum II

Backtracking Tree Depth-First Search Binary Tree

#50

Rank

#226EasyFrequency: 43%

Invert Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#51

Rank

#255MediumFrequency: 41.2%

Verify Preorder Sequence in Binary Search Tree

Array Stack Tree Binary Search Tree Recursion Monotonic Stack Binary Tree

#52

Rank

#789EasyFrequency: 40.8%

Kth Largest Element in a Stream

Tree Design Binary Search Tree Heap (Priority Queue)Binary Tree Data Stream

#53

Rank

#112EasyFrequency: 40.5%

Path Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#54

Rank

#114MediumFrequency: 40.5%

Flatten Binary Tree to Linked List

Linked List Stack Tree Depth-First Search Binary Tree

#55

Rank

#1207MediumFrequency: 40.2%

Delete Nodes And Return Forest

Array Hash Table Tree Depth-First Search Binary Tree

#56

Rank

#117MediumFrequency: 40%

Populating Next Right Pointers in Each Node II

Linked List Tree Depth-First Search Breadth-First Search Binary Tree

#57

Rank

#99MediumFrequency: 39.4%

Recover Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#58

Rank

#1653MediumFrequency: 39.1%

Number of Good Leaf Nodes Pairs

#59

Rank

#2780MediumFrequency: 39.1%

Make Costs of Paths Equal in a Binary Tree

Array Dynamic Programming Greedy Tree Binary Tree

#60

Rank

#437MediumFrequency: 39.1%

Path Sum III

#61

Rank

#896MediumFrequency: 38.5%

Smallest Subtree with all the Deepest Nodes

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor DP on Trees

#62

Rank

#106MediumFrequency: 38.2%

Construct Binary Tree from Inorder and Postorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#63

Rank

#1050MediumFrequency: 37.4%

Construct Binary Search Tree from Preorder Traversal

Array Stack Tree Binary Search Tree Monotonic Stack Binary Tree

#64

Rank

#96MediumFrequency: 36.8%

Unique Binary Search Trees

Math Dynamic Programming Tree Binary Search Tree Binary Tree

#65

Rank

#653EasyFrequency: 35.7%

Two Sum IV - Input is a BST

Hash Table Two Pointers Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#66

Rank

#1544MediumFrequency: 35.7%

Count Good Nodes in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#67

Rank

#930MediumFrequency: 35.6%

All Possible Full Binary Trees

Dynamic Programming Tree Recursion Memoization Binary Tree

#68

Rank

#1008HardFrequency: 35.1%

Binary Tree Cameras

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#69

Rank

#1475HardFrequency: 35.1%

Maximum Sum BST in Binary Tree

Dynamic Programming Tree Depth-First Search Binary Search Tree Binary Tree DP on Trees

#70

Rank

#1218MediumFrequency: 34%

Lowest Common Ancestor of Deepest Leaves

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor DP on Trees

#71

Rank

#1254MediumFrequency: 33%

Deepest Leaves Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#72

Rank

#572EasyFrequency: 31.9%

Subtree of Another Tree

Tree Depth-First Search String Matching Binary Tree Hash Function

#73

Rank

#1114MediumFrequency: 31.3%

Binary Search Tree to Greater Sum Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#74

Rank

#2545HardFrequency: 31.1%

Height of Binary Tree After Subtree Removal Queries

Array Tree Depth-First Search Breadth-First Search Binary Tree

#75

Rank

#1465MediumFrequency: 31.1%

Maximum Product of Splitted Binary Tree

#76

Rank

#652MediumFrequency: 30.4%

Find Duplicate Subtrees

Hash Table Tree Depth-First Search Binary Tree

#77

Rank

#513MediumFrequency: 29.3%

Find Bottom Left Tree Value

Tree Depth-First Search Breadth-First Search Binary Tree

#78

Rank

#784MediumFrequency: 29.3%

Insert into a Binary Search Tree

#79

Rank

#2646MediumFrequency: 29.1%

Kth Largest Sum in a Binary Tree

Tree Breadth-First Search Sorting Binary Tree

#80

Rank

#530EasyFrequency: 28.9%

Minimum Absolute Difference in BST

Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#81

Rank

#1116MediumFrequency: 28.1%

Maximum Level Sum of a Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#82

Rank

#95MediumFrequency: 28.1%

Unique Binary Search Trees II

Dynamic Programming Backtracking Tree Binary Search Tree Binary Tree

#83

Rank

#404EasyFrequency: 28.1%

Sum of Left Leaves

Tree Depth-First Search Breadth-First Search Binary Tree

#84

Rank

#1093HardFrequency: 27.8%

Recover a Tree From Preorder Traversal

#85

Rank

#1285MediumFrequency: 27.8%

Balance a Binary Search Tree

Divide and Conquer Greedy Tree Depth-First Search Binary Search Tree Binary Tree

#86

Rank

#1768MediumFrequency: 27.8%

Design an Expression Tree With Evaluate Function

Array Math Stack Tree Design Binary Tree

#87

Rank

#109MediumFrequency: 27.7%

Convert Sorted List to Binary Search Tree

Linked List Divide and Conquer Tree Binary Search Tree Binary Tree

#88

Rank

#285MediumFrequency: 27.3%

Inorder Successor in BST

Tree Depth-First Search Binary Search Tree Binary Tree

#89

Rank

#333MediumFrequency: 27.3%

Largest BST Subtree

Dynamic Programming Tree Depth-First Search Binary Search Tree Binary Tree DP on Trees

#90

Rank

#654MediumFrequency: 27.3%

Maximum Binary Tree

Array Divide and Conquer Stack Tree Monotonic Stack Binary Tree Cartesian Tree

#91

Rank

#1609EasyFrequency: 27.3%

Find All The Lonely Nodes

Tree Depth-First Search Breadth-First Search Binary Tree

#92

Rank

#3467MediumFrequency: 27.3%

Find the Level of Tree with Minimum Sum

Tree Depth-First Search Breadth-First Search Binary Tree

#93

Rank

#144EasyFrequency: 27.2%

Binary Tree Preorder Traversal

#94

Rank

#222MediumFrequency: 27.2%

Count Complete Tree Nodes

Binary Search Bit Manipulation Tree Binary Tree

#95

Rank

#1498EasyFrequency: 26.7%

Find a Corresponding Node of a Binary Tree in a Clone of That Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#96

Rank

#508MediumFrequency: 26.5%

Most Frequent Subtree Sum

Hash Table Tree Depth-First Search Binary Tree DP on Trees

#97

Rank

#1092MediumFrequency: 26.5%

Maximum Difference Between Node and Ancestor

#98

Rank

#1624MediumFrequency: 26.5%

Clone Binary Tree With Random Pointer

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#99

Rank

#1816MediumFrequency: 26.5%

Lowest Common Ancestor of a Binary Tree IV

Hash Table Tree Depth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#100

Rank

#2677MediumFrequency: 26.5%

Cousins in Binary Tree II

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#101

Rank

#501EasyFrequency: 25.4%

Find Mode in Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#102

Rank

#783EasyFrequency: 25.4%

Search in a Binary Search Tree

#103

Rank

#107MediumFrequency: 25.3%

Binary Tree Level Order Traversal II

#104

Rank

#449MediumFrequency: 25.1%

Serialize and Deserialize BST

String Tree Depth-First Search Breadth-First Search Design Binary Search Tree Binary Tree

#105

Rank

#538MediumFrequency: 25.1%

Convert BST to Greater Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#106

Rank

#1079EasyFrequency: 25.1%

Sum of Root To Leaf Binary Numbers

#107

Rank

#1243MediumFrequency: 25.1%

Sum of Nodes with Even-Valued Grandparent

Tree Depth-First Search Breadth-First Search Binary Tree

#108

Rank

#2558MediumFrequency: 25.1%

Minimum Number of Operations to Sort a Binary Tree by Level

#109

Rank

#637EasyFrequency: 25.1%

Average of Levels in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#110

Rank

#1275MediumFrequency: 25.1%

Validate Binary Tree Nodes

Tree Depth-First Search Breadth-First Search Union-Find Graph Theory Binary Tree

#111

Rank

#1729MediumFrequency: 25.1%

Binary Search Tree Iterator II

Stack Tree Design Binary Search Tree Binary Tree Iterator

#112

Rank

#111EasyFrequency: 25%

Minimum Depth of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#113

Rank

#925MediumFrequency: 24.4%

Construct Binary Tree from Preorder and Postorder Traversal

Array Hash Table Divide and Conquer Tree Binary Tree

#114

Rank

#1150MediumFrequency: 23.6%

Two Sum BSTs

Two Pointers Binary Search Stack Tree Depth-First Search Binary Search Tree Binary Tree

#115

Rank

#1427MediumFrequency: 23.6%

All Elements in Two Binary Search Trees

Tree Depth-First Search Binary Search Tree Sorting Binary Tree

#116

Rank

#1883MediumFrequency: 23.6%

Find Distance in a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree Binary Lifting Lowest Common Ancestor

#117

Rank

#1040MediumFrequency: 23.4%

Maximum Binary Tree II

#118

Rank

#509MediumFrequency: 23.4%

Inorder Successor in BST II

#119

Rank

#988MediumFrequency: 23.3%

Flip Equivalent Binary Trees

#120

Rank

#1030MediumFrequency: 23.3%

Smallest String Starting From Leaf

String Backtracking Tree Depth-First Search Binary Tree

#121

Rank

#606MediumFrequency: 21.9%

Construct String from Binary Tree

#122

Rank

#1021MediumFrequency: 21.9%

Distribute Coins in Binary Tree

#123

Rank

#1157MediumFrequency: 21.9%

Insufficient Nodes in Root to Leaf Paths

#124

Rank

#1450MediumFrequency: 21.9%

Delete Leaves With a Given Value

#125

Rank

#2126MediumFrequency: 21.5%

Count Nodes Equal to Sum of Descendants

#126

Rank

#1731MediumFrequency: 21.5%

Even Odd Tree

#127

Rank

#145EasyFrequency: 20.9%

Binary Tree Postorder Traversal

#128

Rank

#331MediumFrequency: 20.9%

Verify Preorder Serialization of a Binary Tree

#129

Rank

#2567MediumFrequency: 20.9%

Closest Nodes Queries in a Binary Search Tree

Array Binary Search Tree Depth-First Search Binary Search Tree Binary Tree

#130

Rank

#2416EasyFrequency: 20.9%

Evaluate Boolean Binary Tree

#131

Rank

#549MediumFrequency: 20.3%

Binary Tree Longest Consecutive Sequence II

#132

Rank

#663MediumFrequency: 20%

Equal Tree Partition

#133

Rank

#791MediumFrequency: 20%

Split BST

Tree Binary Search Tree Recursion Binary Tree

#134

Rank

#1091MediumFrequency: 20%

Maximum Average Subtree

#135

Rank

#1568MediumFrequency: 20%

Pseudo-Palindromic Paths in a Binary Tree

Bit Manipulation Tree Depth-First Search Breadth-First Search Binary Tree

#136

Rank

#1736HardFrequency: 20%

Build Binary Expression Tree From Infix Expression

#137

Rank

#799EasyFrequency: 19.5%

Minimum Distance Between BST Nodes

Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree

#138

Rank

#2384EasyFrequency: 19.5%

Root Equals Sum of Children

#139

Rank

#832MediumFrequency: 19.4%

Binary Tree Pruning

#140

Rank

#1692HardFrequency: 18%

Number of Ways to Reorder Array to Get Same BST

Array Math Divide and Conquer Dynamic Programming Tree Union-Find Binary Search Tree Memoization Combinatorics Binary Tree Fermat's Little Theorem

#141

Rank

#669MediumFrequency: 18%

Trim a Binary Search Tree

Tree Depth-First Search Binary Search Tree Binary Tree

#142

Rank

#687MediumFrequency: 16.4%

Longest Univalue Path

#143

Rank

#955MediumFrequency: 16.4%

Complete Binary Tree Inserter

Tree Breadth-First Search Design Binary Tree

#144

Rank

#1248MediumFrequency: 16.4%

Binary Tree Coloring Game

#145

Rank

#1387MediumFrequency: 16.4%

Find Elements in a Contaminated Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Design Binary Tree

#146

Rank

#1745MediumFrequency: 16.4%

Find Nearest Right Node in Binary Tree

#147

Rank

#1750MediumFrequency: 16.4%

Check If Two Expression Trees are Equivalent

Hash Table Tree Depth-First Search Binary Tree Counting

#148

Rank

#1796MediumFrequency: 16.4%

Correct a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#149

Rank

#1810MediumFrequency: 16.4%

Change the Root of a Binary Tree

#150

Rank

#2399HardFrequency: 16.4%

Minimum Flips in Binary Tree to Get Result

Dynamic Programming Tree Depth-First Search Binary Tree

#151

Rank

#2843EasyFrequency: 16.4%

Extract Kth Character From The Rope Tree

#152

Rank

#1035EasyFrequency: 15.7%

Cousins in Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#153

Rank

#904EasyFrequency: 14.4%

Leaf-Similar Trees

#154

Rank

#655MediumFrequency: 12.6%

Print Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#155

Rank

#2493MediumFrequency: 12.6%

Reverse Odd Levels of Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#156

Rank

#2060HardFrequency: 12%

Merge BSTs to Create Single BST

Array Hash Table Tree Depth-First Search Binary Search Tree Binary Tree

#157

Rank

#933EasyFrequency: 10.5%

Increasing Order Search Tree

Stack Tree Depth-First Search Binary Search Tree Binary Tree

#158

Rank

#1005EasyFrequency: 10.5%

Univalued Binary Tree

Tree Depth-First Search Breadth-First Search Binary Tree

#159

Rank

#250MediumFrequency: 10.3%

Count Univalue Subtrees

#160

Rank

#1484MediumFrequency: 8%

Linked List in Binary Tree

Linked List Tree Depth-First Search Binary Tree

#161

Rank

#1474MediumFrequency: 7.3%

Longest ZigZag Path in a Binary Tree

Dynamic Programming Tree Depth-First Search Binary Tree DP on Trees

#162

Rank

#563EasyFrequency: 7.2%

Binary Tree Tilt

#163

Rank

#3509MediumFrequency: 5.5%

K-th Largest Perfect Subtree Size in Binary Tree

Tree Depth-First Search Sorting Binary Tree

#164

Rank

#623MediumFrequency: 5%

Add One Row to Tree