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.

解题思路：可以利用hash_map来进行统计实现

char findTheDifference(string s, string t) {

        int a[26] = {0}, lens = s.length(), lent = t.length(), i;

        for(i = 0; i < lens; i++)

            a[s[i] - 'a']++;

        for(i = 0; i < lent; i++)

            if(a[t[i] - 'a'] <= 0)

                break;

            else

                a[t[i] - 'a']--;

        return t[i];

    }