859. Buddy Strings
Given two strings
Example 1:
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 <= 200000 <= B.length <= 20000AandBconsist only of lowercase letters.
思路：给定两个字母A和B的小写字母，当且仅当我们可以在A中交换两个字母以使结果等于B时返回true。三个条件：
A.length() != B.length(): 长度不同 falseA == B, 如果两个值相同，必需要存在重复的字符- 其他情况
A[i] != B[i]只会出现两次
代码如下：
public class BuddyStrings {
public boolean buddyStrings(String A, String B) {
if (A.length() != B.length()) return false;
if (A.equals(B)) {
Set<Character> set = new HashSet<>();
for (char c : A.toCharArray()) {
set.add(c);
}
if (set.size() == A.length()) {
return false;
} else {
return true;
}
} else {
StringBuilder stringBuilderA = new StringBuilder();
StringBuilder stringBuilderB = new StringBuilder();
for (int i = 0; i < A.length(); i++) {
if (A.toCharArray()[i] != B.toCharArray()[i]){
stringBuilderA.append(A.toCharArray()[i]);
stringBuilderB.append(B.toCharArray()[i]);
}
}
if (stringBuilderA.toString().equals(stringBuilderB.reverse().toString())){
return true;
}else {
return false;
}
}
}
}
