DFS & BFS & BackTrack

Trees

Tree

DFS/BFS

• Find cycle 207. Course Schedule

• No. 89: Gray Code (Definition question)

DFS

• No. 93: Restore IP Addresses

• 733. Flood Fill

• 200. Number of Islands

• No. 282: Expression Add Operators

• No. 399: Evaluate Division

• No. 78 Subsets

• No.90 Subsets I

BFS

• 102. Binary Tree Level Order Traversal

• 542. 01 Matrix

• 994. Rotting Oranges

• No. 127. Word Ladder

• No. 126. Word Ladder || (Bidirectional BFS)

BackTrack

• 257. Binary Tree Paths

• No. 22: Generate Parentheses: DFS backtrack

Mixed DFS/BFS + Backtrack + Memorization ⭐️⭐️⭐️⭐️⭐️

• 39. Combination Sum

• 79. Word Search – DFS

  • Pruning: consider freq, can reverse the word, start from low freq.

• 212. Word Search II – backtracking + trie

• 329. Longest Increasing Path in a Matrix – DFS + DP memoization

• 139. Word Break

• 140. Word Break II – DFS + memoization (backtracking with DP)

• 694. Number of Distinct Islands – DFS + canonical shape representation

• 301. Remove Invalid Parentheses – backtracking + pruning