Longest Substring Without Repeating Characters，longestrepeating

Longest Substring Without Repeating Characters，longestrepeating

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.

#include "iostream"
#include "string"
using namespace std;

int lengthofLongestSubstring(string s)
{
	int locs[256];//保存字符上一次出现的位置
	memset(locs, -1, sizeof(locs));	
	int idx = -1, max = 0;//idx为当前子串的开始位置-1
	for (int i = 0; i < s.size(); i++)
	{
		if (locs[s[i]] > idx)//如果当前字符出现过，那么当前子串的起始位置为这个字符上一次出现的位置+1
		{
			idx = locs[s[i]];
		}
		
		if (i - idx > max)
		{
			max = i - idx;
		}
		
		locs[s[i]] = i;
	}
	return max;
}

void main()
{
	//hnwnkuewhsqmgbbuqcljjivswmdkqtbxixmvtrrbljptnsnfwzqfjmafadrrwsofsbcnuvqhffbsaqxwpqcac  12
	//wlrbbmqbhcdarzowkkyhiddqscdxrjmowfrxsjybldbefsarcbynecdyggxxpklorellnmpapqfwkhopkmco  12
	string str ="hnwnkuewhsqmgbbuqcljjivswmdkqtbxixmvtrrbljptnsnfwzqfjmafadrrwsofsbcnuvqhffbsaqxwpqcac";
	cout<<lengthofLongestSubstring(str)<<endl;
}