Week 2 | Day 6

Goal

DFS / Backtracking

Leetcode

• 301 Remove Invalid Parentheses
• 78. Subsets
• 567. Permutation in String
• 79. Word Search
  • Could Trie improves Speed?
• 126 Word Ladder II
• 721. Accounts Merge
• 10. Regular Expression Matching
  • 变种 regex变成"+","*"(我的妈,上来我一看题就知道要挂...我用dp写的,但是天竺小哥说最好用recursion..)