總結：
2.pic.jpg
Example:
17 Letter Combinations of a Phone Number
22 Generate Parentheses
93 Restore IP Addresses: http://www.reibang.com/p/73235b909c01
131 Palindrome Partitioning http://www.reibang.com/p/a2f384836efb
254 Factor Combinations http://www.reibang.com/p/95a3854c2a80
- Android Unlock Patterns http://www.reibang.com/p/52db4a83afa7
Square grid:
79 Word Search http://www.reibang.com/p/0da28fc9cb3e
排列：
46 Permutations
47 Permutations II
267 Palindrome Permutation II http://www.reibang.com/p/2b029852ad35
組合：
78 Subsets
90 Subsets II
77 Combinations
39 Combination Sum
40 Combination Sum II
216 Combination Sum III http://www.reibang.com/p/736adb14a282
Tree:
- Path Sum II
其他： - Generalized Abbreviation
- Matchsticks to Square
