LeetCode: Find the Difference

ASCII就只有256位，用一个array就可以了

public class Solution {
    public char findTheDifference(String s, String t) {
        int[] sNum = new int[256];
        int[] tNum = new int[256];
        for (int i = 0; i < sNum.length; i++) {
            sNum[i] = 0;
            tNum[i] = 0;
        }
        for (int i = 0; i < s.length(); i++) {
            sNum[(int)s.charAt(i)]++;
        }
        for (int i = 0; i < t.length(); i++) {
            tNum[(int)t.charAt(i)]++;
        }
        for (int i = 0; i < 256; i++) {
            if (sNum[i] != tNum[i]) return (char)i;
        }
        return '.';
    }
}