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.

题目含义：给定两个字符串s和t，都只包含小写字母，字符串t是由字符串s打乱顺序且在额外的随机位置上添加一个字符组成，请找出这个字符

方法一：

    public char findTheDifference(String s, String t) {
        char result = 0;
        for (int i=0;i<t.length();i++){
            result += t.charAt(i);
        }

        for (int i=0;i<s.length();i++){
            result -= s.charAt(i);
        }
        return result;  
    }

方法二：

    public char findTheDifference(String s, String t) {
        char result = 0;
        for (int i=0;i<s.length();i++){
            result ^= s.charAt(i);
        }

        for (int i=0;i<t.length();i++){
            result ^= t.charAt(i);
        }
        return result;
    }