摘要： Given a set of distinct integers,S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not co... 阅读全文

摘要： 给定n和k，从1到n中选k个数，存到结果中。其实就是组合问题。例如Ifn= 3， k = 2, 结果是 {1,2], [1,3], [2,3] };思路：利用回溯法。class Solution {public: void dfs77(vector > &ans, vector subans,... 阅读全文

摘要： 给定两个串，S和T，在S中找到包含T的最短子串，如果不能包含，返回空字符。Given a string S and a string T, find the minimum window in S which will contain all the characters in T in compl... 阅读全文