网址:https://leetcode.com/problems/permutation-in-string/ 参考:https://leetcode.com/problems/permutation-in-string/discuss/102588/Java-Solution-Sliding-Window 把s1的各个字母的出现次数记录下来,对s2利用滑动窗口法,逐步移动窗口,判断当前窗口内字符串是否是s1的全排列之一.容易想到,窗口内的字符对应的出现次数要-1.所以,当字符从窗口左端脱离窗口…