[Leetcode] 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:eExplanation:'e' is the letter that was added.

public class Solution {    public char findTheDifference(String s, String t) {        int[] ch=new int[26];        for(int i=0;i<s.length();i++)         ch[s.charAt(i)-'a']+=1;        for(int j=0;j<t.length();j++)         ch[t.charAt(j)-'a']-=1;        for(int k=0;k<26;k++)        if(ch[k]==-1) return (char)(k+'a');        return 'a';     }}