Longest Substring Without Repeating Characters
class Solution { public: int lengthOfLongestSubstring(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function if(s=="") return 0; map<char,int> key; for(char i = 'a';i<='z';i++) key[i] = -1; int count = s.length(); int i = 0; int result = 0; int temp = 0; int pre = 0; while(i<count) { if(key[s[i]]<pre) { temp++; key[s[i]] = i; } else { if(temp>result) { result = temp; } temp = i - key[s[i]]; pre = key[s[i]]; key[s[i]] = i; } i++; } if(temp>result) result = temp; return result; } };