Leetcode389

Find the Difference

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

给出两个字符串，s和t，都是只有小写字母组成的。

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

字符串t是由字符串s其中在随机的位置添加一个字符组成的。

Find the letter that was added in t.

找出在t中增加的字符

Example:

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

Output:
e

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

我一开始的想法就是把每个字符加起来，然后连个字符串相差的字符对应的数，就是对应的不同的字符了，很难说明白就直接看代码好了。
char c = 0;
for (int i=0;i<t.length();i++)
{
    c += t.charAt(i);
}
for (int i=0;i<s.length();i++)
{
    c -= s.charAt(i);
}
return c

之后看了讨论区，发现有一个异或好方法，但是无论怎么想都没想通。只能先记下了。

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