LeetCode 389 Find the Difference

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

Input:
s = "abcd"
t = "abcde"

Output:
e

Explanation:
'e' is the letter that was added.

方法一：Runtime: 6 ms

public char findTheDifference(String s, String t) {
char c = 0;
for (char a : s.toCharArray()) a^=c;
for (char b : t.toCharArray()) b^=c;
return (char) c;
}


方法二：Runtime: 6 ms

public char findTheDifference(String s, String t) {
char[] count = new char[26];
for (char c : s.toCharArray()) count[c - 97]++;
for (char c : t.toCharArray()) if (count[c - 97]-- < 1) return c;
return 'a';
}