Leetcode个人总结10 字符串题(2)

 1 class Solution {
 2 public:
 3     int lengthOfLongestSubstring(string s) {
 4         vector<bool> exist(256, false);
 5         int res = 0;
 6         int start = 0, end = 0;
 7         int N = s.size();
 8         while(end < N) {
 9             if(!exist[s[end]]) {
10                 exist[s[end++]] = true;
11             }
12             else {
13                 exist[s[start++]] = false;
14             }
15             res = max(end-start, res); // already +1 in var: end
16         }
17         return res;
18     }
19 };

 1 class Solution {
 2 public:
 3     string longestCommonPrefix(vector<string> &strs) {
 4         string res;
 5         if(strs.empty()) 
 6             return res;
 7         for(int i = 0; i < strs[0].size(); i++) {
 8             char ch = strs[0][i];
 9             for(int j = 1; j < strs.size(); j++) {
10                 if(strs[j][i] != ch || i == strs[j].size()) {
11                     return res;
12                 }
13             }
14             res.push_back(ch);
15         }
16     }
17 };