29 Search(dfs) and BackTrack

所有search，或求具体方案，就用dfs。求个数用dp。

复杂度是O(答案个数*构造每个答案的时间)

3 Permutation & Combination

22 Generate Parentheses

79 Word Search (L123)

212 Word Search II (L132)

140 Word Break II (L582)

51 N_Queens

52 N_Queens II

37 Sudoku solver

password generate according to list -- U+面经

93 Restore IP Addresses

131 Palindrome Partitioning (L136)

291 Word Pttern II

211 Add and Search Word - Data structure Design (L473)

351 Android Unlock Patterns

425 Word Squares

411 Minimum Unique Word Abbreviation

294 Flip Game II

526 Beautiful Arrangement

L90 k Sum II

282 Expression Add Operators

698 Partition to K Equal Sum Subsets

Divide and conquer

95 Unique Binary Search Tree II

241 Different Ways to Add Parentheses

other related:

290 Word Pattern -- Hash table

293 Flip Game -- String

139 Word Break -- DP

L389 Valid Sudoku

L108 Palindrome Partitionaing II (132)

L89 k Sum - DP