1876. 长度为三且各字符不同的子字符串

1876. 长度为三且各字符不同的子字符串

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C代码：滑动窗口

// 存在三种字符，且不重复、子串数量
int countGoodSubstrings(char * s){int k = 3;int hash[26] = {0};int len = 0;int l = 0;int ans = 0;for (int i = 0; i < strlen(s); ++i) {hash[s[i] - 'a']++;if (hash[s[i] - 'a'] == 1) {++len;}while (hash[s[i] - 'a'] > 1 || len > k) {hash[s[l] - 'a']--;if (hash[s[l] - 'a'] == 0) {--len;}++l;}if (len == k) {++ans;}}return ans;
}

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C代码：规定了次数，一次遍历判断三个元素两两不等

// 存在三种字符，且不重复、子串数量
int countGoodSubstrings(char * s){int res = 0;int n = strlen(s);for (int i = 0; i < n - 2; ++i){if (s[i] != s[i+1] && s[i] != s[i+2] && s[i+1] != s[i+2]) {++res;}}return res;
}