题目
Given two strings A and B of lowercase letters, return true if you can swap two letters in A so the result is equal to B, otherwise, return false.
Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at A[i] and A[j]. For example, swapping at indices 0 and 2 in “abcd” results in “cbad”.
解题思路
分类讨论
- A和B长度不同，返回false
- A和B长度相同，而且为相同字符串，如果存在任一个字符出现的次数大于1，返回True
- A和B长度相同，而且为不同字符串，对应位置组成pair，字母不同的pair数为2，前两个pair相反，返回True
代码
class Solution:
def buddyStrings(self, A: str, B: str) -> bool:
if len(A) != len(B):
return False
if A == B:
s = set()
for a in A:
if a in s:
return True
s.add(a)
return False
pair = []
for a, b in zip(A, B):
if a != b:
pair.append((a, b))
if len(pair) > 2:
return False
return len(pair) == 2 and pair[0] == pair[1][::-1]
