Find_the_Difference.md

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.

Code:

class Solution {
    public char findTheDifference(String s, String t) {
        int[] letters = new int[26];
        for (char c : s.toCharArray()) letters[c - 'a']++;
        for (char c : t.toCharArray()) {
            if (--letters[c - 'a'] < 0) return c;
        }
        return 0;
    }
}

---

• 常规的字符串类型的题目，使用数组作为字符表，存入出现次数；
• 对于字符串s，出现元素则++，对于字符串t，出现元素则--；
• 由于初始化字符串全零，所以当次数小于零时，则返回当前字符；
• 字符类型的返回值，空的情况可以返回0。