Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.

解题思路：用两个标志位来表示不重复字符串的头尾，每次按一个字符长度搜索时，若当前字符不重复则跟新当前字符串长度，否则将字符串长度与最长不重复字符串长度比较，跟新结果。并根据重复的字符串位置确定字符串的起始位置。

#include<iostream>#include<vector>#include<map>#include<string>using namespace std;int lengthOfLongestSubstring(string s) {int LengthLongestSubs = 0;int LengthTmp = 0;map<char, int>CharMap;int IdxBegin = 0;int IdxEnd   = 0;for (; IdxEnd != s.size();++IdxEnd){auto Iter = CharMap.find(s[IdxEnd]);if (Iter == CharMap.end()){CharMap.insert(make_pair(s[IdxEnd], IdxEnd));LengthTmp = IdxEnd + 1 - IdxBegin;//确立不重复字符串的长度}else{LengthLongestSubs = LengthLongestSubs < LengthTmp ? LengthTmp: LengthLongestSubs;int tmp = IdxBegin;IdxBegin = Iter->second+1;//确立新的字符串起始位置for (int i = tmp; i != IdxBegin; ++i)CharMap.erase(s[i]);CharMap.insert(make_pair(s[IdxEnd], IdxEnd));//跟新map}}LengthLongestSubs = LengthLongestSubs < LengthTmp ? LengthTmp : LengthLongestSubs;//避免某些情况，LengthLongestSubs未跟新return LengthLongestSubs;}