LeetCode Solution, Medium, 567. Permutation in String

567. Permutation in String 題目敘述 Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise. In other words, return true if one of s1's permutations is the substring of s2. Example 1: Input: s1 = "ab", s2 = "eidbao...