Tree Interview Questions
Master 223 tree problems frequently asked in technical interviews. These questions test your understanding of treeconcepts and are essential for coding interview success.
223
Total Problems
40
Easy
141
Medium
42
Hard
#314MediumFrequency: 93.4%
Binary Tree Vertical Order Traversal
#1
Rank
#124HardFrequency: 90.2%
Binary Tree Maximum Path Sum
#2
Rank
#1790MediumFrequency: 88.5%
Lowest Common Ancestor of a Binary Tree III
#3
Rank
#4
Rank
#543EasyFrequency: 86.8%
Diameter of Binary Tree
#5
Rank
#236MediumFrequency: 86.4%
Lowest Common Ancestor of a Binary Tree
#6
Rank
#199MediumFrequency: 85.4%
Binary Tree Right Side View
#7
Rank
#2217MediumFrequency: 83.7%
Step-By-Step Directions From a Binary Tree Node to Another
#8
Rank
#1190MediumFrequency: 82.4%
Smallest Common Region
#9
Rank
#230MediumFrequency: 82.3%
Kth Smallest Element in a BST
#10
Rank
#11
Rank
#4180MediumFrequency: 78.4%
Pythagorean Distance Nodes in a Tree
#12
Rank
#975EasyFrequency: 78%
Range Sum of BST
#13
Rank
#366MediumFrequency: 76.7%
Find Leaves of Binary Tree
#14
Rank
#2905HardFrequency: 71.9%
Count Paths That Can Form a Palindrome in a Tree
#15
Rank
#16
Rank
#3875HardFrequency: 69.8%
Maximum Good Subtree Score
#17
Rank
#1029HardFrequency: 69.1%
Vertical Order Traversal of a Binary Tree
#18
Rank
#235MediumFrequency: 66.5%
Lowest Common Ancestor of a Binary Search Tree
#19
Rank
#893MediumFrequency: 65.7%
All Nodes Distance K in Binary Tree
#20
Rank
#108EasyFrequency: 65.5%
Convert Sorted Array to Binary Search Tree
#21
Rank
#104EasyFrequency: 65%
Maximum Depth of Binary Tree
#22
Rank
#758MediumFrequency: 63.7%
Convert Binary Search Tree to Sorted Doubly Linked List
#23
Rank
#101EasyFrequency: 63.4%
Symmetric Tree
#24
Rank
#297HardFrequency: 63.4%
Serialize and Deserialize Binary Tree
#25
Rank
#2584MediumFrequency: 62.5%
Number of Nodes With Value One
#26
Rank
#3977HardFrequency: 62.5%
Count Non Adjacent Subsets in a Rooted Tree
#27
Rank
#270EasyFrequency: 61.8%
Closest Binary Search Tree Value
#28
Rank
#272HardFrequency: 61.6%
Closest Binary Search Tree Value II
#29
Rank
#743MediumFrequency: 61.1%
Closest Leaf in a Binary Tree
#30
Rank
#173MediumFrequency: 60.9%
Binary Search Tree Iterator
#31
Rank
#671EasyFrequency: 60.7%
Second Minimum Node In a Binary Tree
#32
Rank
#2175MediumFrequency: 59.9%
Count Nodes With the Highest Score
#33
Rank
#105MediumFrequency: 59.3%
Construct Binary Tree from Preorder and Inorder Traversal
#34
Rank
#103MediumFrequency: 55.5%
Binary Tree Zigzag Level Order Traversal
#35
Rank
#3497HardFrequency: 55.1%
Find the Last Marked Nodes in Tree
#36
Rank
#102MediumFrequency: 54.4%
Binary Tree Level Order Traversal
#37
Rank
#998MediumFrequency: 54.4%
Check Completeness of a Binary Tree
#38
Rank
#39
Rank
#2461MediumFrequency: 52.9%
Amount of Time for Binary Tree to Be Infected
#40
Rank
#662MediumFrequency: 52.9%
Maximum Width of Binary Tree
#41
Rank
#98MediumFrequency: 52.8%
Validate Binary Search Tree
#42
Rank
#2347MediumFrequency: 52.7%
Count Nodes Equal to Average of Subtree
#43
Rank
#337MediumFrequency: 52.1%
House Robber III
#44
Rank
#341MediumFrequency: 51%
Flatten Nested List Iterator
#45
Rank
#1780MediumFrequency: 50.6%
Lowest Common Ancestor of a Binary Tree II
#46
Rank
#47
Rank
#48
Rank
#116MediumFrequency: 48.8%
Populating Next Right Pointers in Each Node
#49
Rank
#617EasyFrequency: 48.8%
Merge Two Binary Trees
#50
Rank
#257EasyFrequency: 48.7%
Binary Tree Paths
#51
Rank
#100EasyFrequency: 48.1%
Same Tree
#52
Rank
#536MediumFrequency: 47.5%
Construct Binary Tree from String
#53
Rank
#690MediumFrequency: 47.5%
Employee Importance
#54
Rank
#1643MediumFrequency: 47.5%
Number of Nodes in the Sub-Tree With the Same Label
#55
Rank
#1820HardFrequency: 47.5%
Number Of Ways To Reconstruct A Tree
#56
Rank
#2306MediumFrequency: 47.5%
Create Binary Tree From Descriptions
#57
Rank
#2364HardFrequency: 44.8%
Longest Path With Different Adjacent Characters
#58
Rank
#515MediumFrequency: 44.7%
Find Largest Value in Each Tree Row
#59
Rank
#94EasyFrequency: 44.2%
Binary Tree Inorder Traversal
#60
Rank
#298MediumFrequency: 44%
Binary Tree Longest Consecutive Sequence
#61
Rank
#62
Rank
#226EasyFrequency: 43%
Invert Binary Tree
#63
Rank
#64
Rank
#255MediumFrequency: 41.2%
Verify Preorder Sequence in Binary Search Tree
#65
Rank
#789EasyFrequency: 40.8%
Kth Largest Element in a Stream
#66
Rank
#1554MediumFrequency: 40.7%
Minimum Time to Collect All Apples in a Tree
#67
Rank
#112EasyFrequency: 40.5%
Path Sum
#68
Rank
#114MediumFrequency: 40.5%
Flatten Binary Tree to Linked List
#69
Rank
#1207MediumFrequency: 40.2%
Delete Nodes And Return Forest
#70
Rank
#117MediumFrequency: 40%
Populating Next Right Pointers in Each Node II
#71
Rank
#99MediumFrequency: 39.4%
Recover Binary Search Tree
#72
Rank
#765HardFrequency: 39.4%
Serialize and Deserialize N-ary Tree
#73
Rank
#1653MediumFrequency: 39.1%
Number of Good Leaf Nodes Pairs
#74
Rank
#1177MediumFrequency: 39.1%
Tree Diameter
#75
Rank
#2780MediumFrequency: 39.1%
Make Costs of Paths Equal in a Binary Tree
#76
Rank
#77
Rank
#582MediumFrequency: 39.1%
Kill Process
#78
Rank
#896MediumFrequency: 38.5%
Smallest Subtree with all the Deepest Nodes
#79
Rank
#106MediumFrequency: 38.2%
Construct Binary Tree from Inorder and Postorder Traversal
#80
Rank
#2564MediumFrequency: 37.9%
Most Profitable Path in a Tree
#81
Rank
#1050MediumFrequency: 37.4%
Construct Binary Search Tree from Preorder Traversal
#82
Rank
#96MediumFrequency: 36.8%
Unique Binary Search Trees
#83
Rank
#653EasyFrequency: 35.7%
Two Sum IV - Input is a BST
#84
Rank
#1544MediumFrequency: 35.7%
Count Good Nodes in Binary Tree
#85
Rank
#930MediumFrequency: 35.6%
All Possible Full Binary Trees
#86
Rank
#1665MediumFrequency: 35.6%
Diameter of N-Ary Tree
#87
Rank
#1008HardFrequency: 35.1%
Binary Tree Cameras
#88
Rank
#1475HardFrequency: 35.1%
Maximum Sum BST in Binary Tree
#89
Rank
#1218MediumFrequency: 34%
Lowest Common Ancestor of Deepest Leaves
#90
Rank
#1254MediumFrequency: 33%
Deepest Leaves Sum
#91
Rank
#572EasyFrequency: 31.9%
Subtree of Another Tree
#92
Rank
#863HardFrequency: 31.8%
Sum of Distances in Tree
#93
Rank
#1114MediumFrequency: 31.3%
Binary Search Tree to Greater Sum Tree
#94
Rank
#3058HardFrequency: 31.3%
Maximum Number of K-Divisible Components
#95
Rank
#1492MediumFrequency: 31.3%
Time Needed to Inform All Employees
#96
Rank
#2545HardFrequency: 31.1%
Height of Binary Tree After Subtree Removal Queries
#97
Rank
#1465MediumFrequency: 31.1%
Maximum Product of Splitted Binary Tree
#98
Rank
#652MediumFrequency: 30.4%
Find Duplicate Subtrees
#99
Rank
#513MediumFrequency: 29.3%
Find Bottom Left Tree Value
#100
Rank
#784MediumFrequency: 29.3%
Insert into a Binary Search Tree
#101
Rank
#2568MediumFrequency: 29.3%
Minimum Fuel Cost to Report to the Capital
#102
Rank
#4151HardFrequency: 29.3%
Maximum Subgraph Score in a Tree
#103
Rank
#2646MediumFrequency: 29.1%
Kth Largest Sum in a Binary Tree
#104
Rank
#530EasyFrequency: 28.9%
Minimum Absolute Difference in BST
#105
Rank
#1116MediumFrequency: 28.1%
Maximum Level Sum of a Binary Tree
#106
Rank
#95MediumFrequency: 28.1%
Unique Binary Search Trees II
#107
Rank
#404EasyFrequency: 28.1%
Sum of Left Leaves
#108
Rank
#1093HardFrequency: 27.8%
Recover a Tree From Preorder Traversal
#109
Rank
#1285MediumFrequency: 27.8%
Balance a Binary Search Tree
#110
Rank
#1768MediumFrequency: 27.8%
Design an Expression Tree With Evaluate Function
#111
Rank
#3675HardFrequency: 27.8%
Maximize Sum of Weights after Edge Removals
#112
Rank
#109MediumFrequency: 27.7%
Convert Sorted List to Binary Search Tree
#113
Rank
#285MediumFrequency: 27.3%
Inorder Successor in BST
#114
Rank
#333MediumFrequency: 27.3%
Largest BST Subtree
#115
Rank
#654MediumFrequency: 27.3%
Maximum Binary Tree
#116
Rank
#1201MediumFrequency: 27.3%
Delete Tree Nodes
#117
Rank
#1609EasyFrequency: 27.3%
Find All The Lonely Nodes
#118
Rank
#3304MediumFrequency: 27.3%
Maximum Subtree of the Same Color
#119
Rank
#3467MediumFrequency: 27.3%
Find the Level of Tree with Minimum Sum
#120
Rank
#1296HardFrequency: 27.2%
Kth Ancestor of a Tree Node
#121
Rank
#144EasyFrequency: 27.2%
Binary Tree Preorder Traversal
#122
Rank
#222MediumFrequency: 27.2%
Count Complete Tree Nodes
#123
Rank
#1498EasyFrequency: 26.7%
Find a Corresponding Node of a Binary Tree in a Clone of That Tree
#124
Rank
#508MediumFrequency: 26.5%
Most Frequent Subtree Sum
#125
Rank
#1092MediumFrequency: 26.5%
Maximum Difference Between Node and Ancestor
#126
Rank
#1624MediumFrequency: 26.5%
Clone Binary Tree With Random Pointer
#127
Rank
#1816MediumFrequency: 26.5%
Lowest Common Ancestor of a Binary Tree IV
#128
Rank
#2677MediumFrequency: 26.5%
Cousins in Binary Tree II
#129
Rank
#501EasyFrequency: 25.4%
Find Mode in Binary Search Tree
#130
Rank
#783EasyFrequency: 25.4%
Search in a Binary Search Tree
#131
Rank
#107MediumFrequency: 25.3%
Binary Tree Level Order Traversal II
#132
Rank
#3439HardFrequency: 25.3%
Find Minimum Diameter After Merging Two Trees
#133
Rank
#449MediumFrequency: 25.1%
Serialize and Deserialize BST
#134
Rank
#538MediumFrequency: 25.1%
Convert BST to Greater Tree
#135
Rank
#1079EasyFrequency: 25.1%
Sum of Root To Leaf Binary Numbers
#136
Rank
#1243MediumFrequency: 25.1%
Sum of Nodes with Even-Valued Grandparent
#137
Rank
#2558MediumFrequency: 25.1%
Minimum Number of Operations to Sort a Binary Tree by Level
#138
Rank
#637EasyFrequency: 25.1%
Average of Levels in Binary Tree
#139
Rank
#1275MediumFrequency: 25.1%
Validate Binary Tree Nodes
#140
Rank
#1729MediumFrequency: 25.1%
Binary Search Tree Iterator II
#141
Rank
#111EasyFrequency: 25%
Minimum Depth of Binary Tree
#142
Rank
#925MediumFrequency: 24.4%
Construct Binary Tree from Preorder and Postorder Traversal
#143
Rank
#1150MediumFrequency: 23.6%
Two Sum BSTs
#144
Rank
#1427MediumFrequency: 23.6%
All Elements in Two Binary Search Trees
#145
Rank
#1883MediumFrequency: 23.6%
Find Distance in a Binary Tree
#146
Rank
#147
Rank
#148
Rank
#988MediumFrequency: 23.3%
Flip Equivalent Binary Trees
#149
Rank
#1030MediumFrequency: 23.3%
Smallest String Starting From Leaf
#150
Rank
#3603HardFrequency: 23.3%
Check if DFS Strings Are Palindromes
#151
Rank
#2505HardFrequency: 22.1%
Number of Good Paths
#152
Rank
#606MediumFrequency: 21.9%
Construct String from Binary Tree
#153
Rank
#1021MediumFrequency: 21.9%
Distribute Coins in Binary Tree
#154
Rank
#1157MediumFrequency: 21.9%
Insufficient Nodes in Root to Leaf Paths
#155
Rank
#1450MediumFrequency: 21.9%
Delete Leaves With a Given Value
#156
Rank
#2400HardFrequency: 21.9%
Minimum Score After Removals on a Tree
#157
Rank
#3218HardFrequency: 21.9%
Find Number of Coins to Place in Tree Nodes
#158
Rank
#4072HardFrequency: 21.9%
Total Sum of Interaction Cost in Tree Groups
#159
Rank
#2126MediumFrequency: 21.5%
Count Nodes Equal to Sum of Descendants
#160
Rank
#161
Rank
#145EasyFrequency: 20.9%
Binary Tree Postorder Traversal
#162
Rank
#331MediumFrequency: 20.9%
Verify Preorder Serialization of a Binary Tree
#163
Rank
#2567MediumFrequency: 20.9%
Closest Nodes Queries in a Binary Search Tree
#164
Rank
#2416EasyFrequency: 20.9%
Evaluate Boolean Binary Tree
#165
Rank
#549MediumFrequency: 20.3%
Binary Tree Longest Consecutive Sequence II
#166
Rank
#167
Rank
#168
Rank
#169
Rank
#1568MediumFrequency: 20%
Pseudo-Palindromic Paths in a Binary Tree
#170
Rank
#1634MediumFrequency: 20%
Clone N-ary Tree
#171
Rank
#1736HardFrequency: 20%
Build Binary Expression Tree From Infix Expression
#172
Rank
#799EasyFrequency: 19.5%
Minimum Distance Between BST Nodes
#173
Rank
#174
Rank
#175
Rank
#1650MediumFrequency: 18%
Find Root of N-Ary Tree
#176
Rank
#1692HardFrequency: 18%
Number of Ways to Reorder Array to Get Same BST
#177
Rank
#178
Rank
#2104MediumFrequency: 18%
Operations on Tree
#179
Rank
#669MediumFrequency: 18%
Trim a Binary Search Tree
#180
Rank
#687MediumFrequency: 16.4%
Longest Univalue Path
#181
Rank
#955MediumFrequency: 16.4%
Complete Binary Tree Inserter
#182
Rank
#1248MediumFrequency: 16.4%
Binary Tree Coloring Game
#183
Rank
#1387MediumFrequency: 16.4%
Find Elements in a Contaminated Binary Tree
#184
Rank
#185
Rank
#1745MediumFrequency: 16.4%
Find Nearest Right Node in Binary Tree
#186
Rank
#1750MediumFrequency: 16.4%
Check If Two Expression Trees are Equivalent
#187
Rank
#1796MediumFrequency: 16.4%
Correct a Binary Tree
#188
Rank
#1810MediumFrequency: 16.4%
Change the Root of a Binary Tree
#189
Rank
#1875HardFrequency: 16.4%
Tree of Coprimes
#190
Rank
#2399HardFrequency: 16.4%
Minimum Flips in Binary Tree to Get Result
#191
Rank
#2843EasyFrequency: 16.4%
Extract Kth Character From The Rope Tree
#192
Rank
#3191MediumFrequency: 16.4%
Maximum Score After Applying Operations on a Tree
#193
Rank
#1493HardFrequency: 16.4%
Frog Position After T Seconds
#194
Rank
#3909MediumFrequency: 16.4%
Minimum Increments to Equalize Leaf Paths
#195
Rank
#1035EasyFrequency: 15.7%
Cousins in Binary Tree
#196
Rank
#197
Rank
#3307HardFrequency: 14.4%
Find the Maximum Sum of Node Values
#198
Rank
#655MediumFrequency: 12.6%
Print Binary Tree
#199
Rank
#2493MediumFrequency: 12.6%
Reverse Odd Levels of Binary Tree
#200
Rank
#2060HardFrequency: 12%
Merge BSTs to Create Single BST
#201
Rank
#202
Rank
#933EasyFrequency: 10.5%
Increasing Order Search Tree
#203
Rank
#1005EasyFrequency: 10.5%
Univalued Binary Tree
#204
Rank
#3633MediumFrequency: 10.5%
Maximize the Number of Target Nodes After Connecting Trees I
#205
Rank
#3842HardFrequency: 10.5%
Number of Ways to Assign Edge Weights II
#206
Rank
#207
Rank
#250MediumFrequency: 10.3%
Count Univalue Subtrees
#208
Rank
#3645HardFrequency: 8.1%
Maximize the Number of Target Nodes After Connecting Trees II
#209
Rank
#3900HardFrequency: 8.1%
Find Weighted Median Node in Tree
#210
Rank
#1484MediumFrequency: 8%
Linked List in Binary Tree
#211
Rank
#3844MediumFrequency: 8%
Number of Ways to Assign Edge Weights I
#212
Rank
#1474MediumFrequency: 7.3%
Longest ZigZag Path in a Binary Tree
#213
Rank
#214
Rank
#215
Rank
#774EasyFrequency: 7.2%
Maximum Depth of N-ary Tree
#216
Rank
#3509MediumFrequency: 5.5%
K-th Largest Perfect Subtree Size in Binary Tree
#217
Rank
#3798HardFrequency: 5.5%
Longest Special Path II
#218
Rank
#3854HardFrequency: 5.5%
Maximum Profit from Trading Stocks with Discounts
#219
Rank
#623MediumFrequency: 5%
Add One Row to Tree
#220
Rank
#2420HardFrequency: 5%
Closest Node to Path in Tree
#221
Rank
#3957HardFrequency: 5%
Sum of Perfect Square Ancestors
#222
Rank
#2445MediumFrequency: 5%
Reachable Nodes With Restrictions
#223
Rank
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