859.-buddy-strings.md

859. Buddy Strings

class Solution:
    def buddyStrings(self, A: str, B: str) -> bool:
     ## 这居然是简单
     ## 重要是一个个第分类讨论
        if len(A) != len(B) : return False
        if A == B and len(set(A)) < len(A): return True
        ans = []
        for a,b in zip(A, B):
            if a != b:
                ans.append((a,b))
        return len(ans) == 2 and ans[0] == ans[1][::-1]