Map<Character, Integer> window = new HashMap<>();
Map<Character, Integer> need = new HashMap<>();
//需要的字符传入need
for (char c : t.toCharArray()) {
    need.put(c, need.getOrDefault(c, 0) + 1);
}
int left = 0;
int right = 0;
while (right < s.length()) {
    //c是移入窗口的字符
    char c = s.charAt(right);
    //右边界右移
    right++;

    //进入窗口的一系列操作.....
    
    //当满足时,需要进行窗口缩减
    while (win收缩) {
        char d = s.charAt(left);
        //左边界右移
        left++;

        //出窗口的一系列操作.....
    }
}   

暂存，有时间回来解释