Episode 7 — DSA with JavaScript / 7.16 — Trees

7.16 — Quick Revision: Trees

<< Overview

Key concepts

Traversal summary

OrderSequenceUse
InorderL→Root→RSorted for BST
PreorderRoot→L→RCopy/serialize
PostorderL→R→RootDelete/evaluate
LevelBFSLayer-by-layer

Key formulas

  • Height = 1 + max(left, right)
  • Diameter = max(leftH + rightH + 2)
  • Perfect tree nodes = 2^(h+1) - 1
  • Min height = floor(log₂n)

Self-check drill

SC-001

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-002

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-003

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-004

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-005

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-006

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-007

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-008

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-009

  • Q: DFS uses?
  • A: Stack or recursion

SC-010

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-011

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-012

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-013

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-014

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-015

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-016

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-017

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-018

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-019

  • Q: DFS uses?
  • A: Stack or recursion

SC-020

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-021

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-022

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-023

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-024

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-025

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-026

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-027

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-028

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-029

  • Q: DFS uses?
  • A: Stack or recursion

SC-030

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-031

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-032

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-033

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-034

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-035

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-036

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-037

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-038

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-039

  • Q: DFS uses?
  • A: Stack or recursion

SC-040

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-041

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-042

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-043

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-044

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-045

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-046

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-047

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-048

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-049

  • Q: DFS uses?
  • A: Stack or recursion

SC-050

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-051

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-052

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-053

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-054

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-055

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-056

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-057

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-058

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-059

  • Q: DFS uses?
  • A: Stack or recursion

SC-060

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-061

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-062

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-063

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-064

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-065

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-066

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-067

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-068

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-069

  • Q: DFS uses?
  • A: Stack or recursion

SC-070

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-071

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-072

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-073

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-074

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-075

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-076

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-077

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-078

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-079

  • Q: DFS uses?
  • A: Stack or recursion

SC-080

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-081

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-082

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-083

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-084

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-085

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-086

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-087

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-088

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-089

  • Q: DFS uses?
  • A: Stack or recursion

SC-090

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-091

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-092

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-093

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-094

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-095

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-096

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-097

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-098

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-099

  • Q: DFS uses?
  • A: Stack or recursion

SC-100

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-101

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-102

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-103

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-104

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-105

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-106

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-107

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-108

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-109

  • Q: DFS uses?
  • A: Stack or recursion

SC-110

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-111

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-112

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-113

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-114

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-115

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-116

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-117

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-118

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-119

  • Q: DFS uses?
  • A: Stack or recursion

SC-120

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-121

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-122

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-123

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-124

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-125

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-126

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-127

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-128

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-129

  • Q: DFS uses?
  • A: Stack or recursion

SC-130

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-131

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-132

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-133

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-134

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-135

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-136

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-137

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-138

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-139

  • Q: DFS uses?
  • A: Stack or recursion

SC-140

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-141

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-142

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-143

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-144

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-145

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-146

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-147

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-148

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-149

  • Q: DFS uses?
  • A: Stack or recursion

SC-150

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-151

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-152

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-153

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-154

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-155

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-156

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-157

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-158

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-159

  • Q: DFS uses?
  • A: Stack or recursion

SC-160

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-161

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-162

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-163

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-164

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-165

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-166

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-167

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-168

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-169

  • Q: DFS uses?
  • A: Stack or recursion

SC-170

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-171

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-172

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-173

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-174

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-175

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-176

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-177

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-178

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-179

  • Q: DFS uses?
  • A: Stack or recursion

SC-180

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-181

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-182

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-183

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-184

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-185

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-186

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-187

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-188

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-189

  • Q: DFS uses?
  • A: Stack or recursion

SC-190

  • Q: Invert tree?
  • A: Swap left and right recursively

SC-191

  • Q: Tree traversal types?
  • A: Inorder, preorder, postorder, level-order

SC-192

  • Q: Inorder gives?
  • A: Sorted order for BST

SC-193

  • Q: Height formula?
  • A: 1 + max(left height, right height)

SC-194

  • Q: Diameter?
  • A: Longest path between any two nodes

SC-195

  • Q: LCA approach?
  • A: Recurse both sides, return found node

SC-196

  • Q: Balanced tree?
  • A: |left height - right height| <= 1 for all nodes

SC-197

  • Q: Full vs Complete?
  • A: Full: 0 or 2 children. Complete: filled left to right

SC-198

  • Q: Level-order uses?
  • A: Queue (BFS)

SC-199

  • Q: DFS uses?
  • A: Stack or recursion

SC-200

  • Q: Invert tree?
  • A: Swap left and right recursively