LeetCode: 3. Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.
Examples:
Given “abcabcbb”, the answer is “abc”, which the length is 3.
Given “bbbbb”, the answer is “b”, with the length of 1.
Given “pwwkew”, the answer is “wke”, with the length of 3.
Note that the answer must be a substring, “pwke” is a subsequence and not a substring.

在这里做个笔记，以后也能看到，自己居然那么蠢地用那么蠢的办法( ▼-▼ )
求两个相同字母的最大距离就好了嘛：
abcabcbb–两个a之间的距离就是3了
abcba–两个a之间是4，两个b之间是2，在发现b有重复的时候，用第二个b的位置减去a的位置就好了，4-1 =3
用一个数组来存放字母的位置，再一个标号标注子字符串的起始位置，ldx = -1，拿abcba来举例：
loc[a] = 0
loc[b] = 1
loc[c] =2
loc[b] = 3 大于原来的 1，ldx = 1,最大长度就是2-（-1） = 3
干巴爹，继续努力！

#include<iostream>#include<string>using namespace std;int main(){    string s;    cin >> s;    int locs[256];    int ldx = -1;    int max = 0;    memset(locs, -1, sizeof(locs));    for (int i = 0; i < s.length(); i++){        if (locs[s[i]]>ldx){            ldx = locs[s[i]];        }        if ((i - ldx) > max){            max = i - ldx;        }        locs[s[i]] = i;    }    cout << max << endl;    return 0;}