剑指 Offer 48. 最长不含重复字符的子字符串https://leetcode.cn/problems/zui-chang-bu-han-zhong-fu-zi-fu-de-zi-zi-fu-chuan-lcof/

dp

注意：缩小 不含重复字符子串 时的写法

dp_1 = min(i - charToIndex[s[i]], dp_0 + 1);

int lengthOfLongestSubstring(string s) {int n = s.size();// base caseif (n < 2){return n;}unordered_map<char, int> charToIndex;int dp_0 = 1;int dp_1 = 1;charToIndex.insert({ s[0],0 });int res = 1;for (int i = 1; i < n; ++i){if (charToIndex.count(s[i])){dp_1 = min(i - charToIndex[s[i]], dp_0 + 1);charToIndex[s[i]] = i;}else{dp_1 = dp_0 + 1;charToIndex.insert({ s[i],i });}dp_0 = dp_1;res = max(res, dp_1);}return res;
}