2015.4.17
子集
T78.cpp
https://leetcode.com/problems/subsets/
T90.cpp
https://leetcode.com/problems/subsets-ii/
C++ vector用法
http://developer.51cto.com/art/201002/183645.htm
2015.4.19
C++ string
http://www.cnblogs.com/gnuhpc/archive/2012/12/09/2810127.html
2月29日——直接做就好???
http://hihocoder.com/contest/msbop2015qual/problem/1
回文字符序列 ——DP
http://hihocoder.com/contest/msbop2015qual/problem/2
