https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/

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class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        //滑动窗口裸题
        //s 由英文字母、数字、符号和空格组成 ????????
        if(s == ""){
            return 0;
        }
        s = ' ' + s;
        //cout << s << '\n';
        int len = s.size();
        int a[50010];
        int tmp[300];
        for(int i = 0 ; i < 300 ; i++){
            tmp[i] = 0;
        }
        for(int i = 1 ; i < len ; i++) {
            //确定前一个相同字母位置
            //cout << s[i] - 'a' << ' ' << tmp[s[i] - 'a'] <<"?\n";
            if(tmp[s[i]] == 0){
                a[i] = 0;
                tmp[s[i]] = i;
            }
            else {
                a[i] = tmp[s[i]];
                tmp[s[i]] = i;
            }
            //cout << a[i] << '\n';
        }

        int ans = 1;
        int top, end;
        top = end = 1;
        for(int i = 2; i < len ; i++){
            if(a[i] < top){
                end++;
                ans = max(ans, end - top + 1); 
            }
            else if(a[i] == top){
                top++;
                end++;
                ans = max(ans, end - top + 1);
            }
            else {
                top = a[i] + 1;
                end++;
                ans = max(ans, end - top + 1);
            }
        }
        return ans;
    }
};