NumKLenSubstrNoRepeats1100

[underwindfall]

• https://leetcode-cn.com/problems/find-k-length-substrings-with-no-repeated-characters/

• 思路

  • 滑动窗口

• [x] 刷15mins

• [x] 刷5mins

 // time O(n)
    // space O(m)
    public int numKLenSubstrNoRepeats(String s, int k) {
        if (k > 26)
            return 0;
        int answer = 0;
        int n = s.length();
        int left = 0, right = 0;
        int[] freq = new int[26];
        while (right < n) {
            freq[s.charAt(right) - 'a']++;

            while (freq[s.charAt(right) - 'a'] > 1) {
                freq[s.charAt(left) - 'a']--;
                left++;
            }

            if (right - left + 1 == k) {
                answer++;
                freq[s.charAt(left) - 'a']--;
                left++;
            }
            right++;
        }
        return answer;
    }