leetcode 76. Minimum Window Substring 最小覆盖子串

https://leetcode.com/problems/minimum-window-substring/
https://leetcode.cn/problems/minimum-window-substring/

76. 最小覆盖子串 Minimum Window Substring 【LeetCode 力扣官方题解】
    https://www.bilibili.com/video/BV1aK4y1t7Qd

https://fuxuemingzhu.cn/leetcode/76.html

https://github.com/changgyhub/leetcode_101

https://www.cnblogs.com/grandyang/p/4340948.html

public String minWindow(String s, String t) {
    // 定义一个字符频率数组来记录t字符串中每个字符出现的次数
    int[] chars = new int[128];
    boolean[] flag = new boolean[128];
    for (char c : t.toCharArray()) {
        chars[c]++;
        flag[c] = true;
    }

    // 定义左指针
    int left = 0;
    // 记录滑动窗口中包含t中字符的数量
    int cnt = 0;
    // 记录最小滑动窗口的左边界指针
    int minLeft = 0;
    // 记录最小滑动窗口的大小
    int minSize = s.length() + 1;
    // 向右滑动右指针
    for (int right = 0; right < s.length(); right++) {
        char c = s.charAt(right);
        if (flag[c]) {
            chars[c]--;
            if (chars[c] >= 0) {
                cnt++;
            }
            while (cnt == t.length()) {
                if (right - left + 1 < minSize) {
                    minLeft = left;
                    minSize = right - left + 1;
                }
                if (flag[s.charAt(left)]) {
                    chars[s.charAt(left)]++;
                    if (chars[s.charAt(left)] > 0) {
                        cnt--;
                    }
                }
                left++;
            }
        }
    }
    return minSize > s.length() ? "" : s.substring(minLeft, minLeft + minSize);
}

• 2022/05/13 看着别人的解题思路能够勉强写出实现，让用自己的的话写出来并教会别人难呀