242.有效的字母异位词

题目：[https://leetcode-cn.com/problems/valid-anagram/description/]
思路：分别对于字母出现次数进行统计，完全相同的即为异位词

class Solution {
public:
    bool isAnagram(string s, string t) {
        map<char,int> ss,tt;
        for (auto &v:s) {
            ++ss[v];
        }
        for (auto &v:t) {
            ++tt[v];
        }
        if (ss==tt) {
            return true;
        }
        return false;
    }
};