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.

使用库里的 hashMap 可能有点慢 ，自己写一个用字母值做映射的count数组就好了。

class Solution {
    public char findTheDifference(String s, String t) {
        int[] count = new int [26];
        char result=' ' ;
        for(int i = 0 ;i<s.length();i++)
        {
            int index = (int)(s.charAt(i)-'a');
            count[index]++;
        }
         for(int i = 0 ;i<t.length();i++)
         {
              int index = (int)(t.charAt(i)-'a');
             if(count[index]>0)
               count[index]--;
             else
                 result=t.charAt(i);
         }
        return result;
    }
}