Given two strings A and B of lowercase letters, return true if and only if we can swap two letters in A so that the result equals B.
Example 1:
Input: A = “ab”, B = “ba”
Output: true
Example 2:
Input: A = “ab”, B = “ab”
Output: false
Example 3:
Input: A = “aa”, B = “aa”
Output: true
Example 4:
Input: A = “aaaaaaabc”, B = “aaaaaaacb”
Output: true
Example 5:
Input: A = “”, B = “aa”
Output: false
Note:
0 <= A.length <= 20000
0 <= B.length <= 20000
A and B consist only of lowercase letters.
Solution
class Solution {
public boolean buddyStrings(String A, String B) {
if (A == null || B == null || A.length() != B.length()) return false;
char[] s1 = A.toCharArray();
char[] s2 = B.toCharArray();
if (A.equals(B)) {
int[] dict = new int[26];
for (char ch: s1) {
dict[ch-‘a’]++;
if (dict[ch-‘a’] >= 2) return true;
}
return false;
}
List<Integer> diffIndex = new ArrayList<>();
for (int i = 0; i < s1.length; i++) {
if (s1[i] != s2[i]) diffIndex.add(i);
}
if (diffIndex.size() != 2) return false;
int i = diffIndex.get(0), j = diffIndex.get(1);
if (A.charAt(i) == B.charAt(j) && A.charAt(j) == B.charAt(i)) return true;
return false;
}
}