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leetcode longest substring without repeating characters

admin 11月 11, 2020 0

文章目录

tips

求没有重复字符的最长子串
memset(who, value, length)
left记录子串的最左边界，如果当前字符在left右面出现过，最更新left
time complexcity: O(N)
space complexcity: O(1)

class  {
public:
    int lengthOfLongestSubstring(string s) {
        int left = 0, ans = 0;
        int last[255];
        memset(last, -1, sizeof(last));
        for(int i = 0; i < s.size(); ++i) {
            if(last[s[i]] >= left) {
                left = last[s[i]] + 1;
            }
            last[s[i]] = i;
            ans = max(ans, i - left + 1);
        }
        return ans;
    }
};