242. Valid Anagram

题目来源【Leetcode】

Given two strings s and t, write a function to determine if t is an anagram of s.

For example,
s = “anagram”, t = “nagaram”, return true.
s = “rat”, t = “car”, return false.

Note:
You may assume the string contains only lowercase alphabets.

这道题就用数组来做，先将参照的字符串的每个字母出现的次数记录，再从给的字符串开始一个一个减，如果出现负数，则肯定不是；

class Solution {
public:
    bool isAnagram(string s, string t) {
        int sl = s.length();
        int tl = t.length();
        if(sl != tl) return false;
        int a[200];
        memset(a,0,sizeof(a));
        for(int i = 0; i < sl; i++){
            a[s[i]]++;
        }
        for(int i = 0; i < tl; i++){
            a[t[i]]--;
            if(a[t[i]] < 0) return false;
        }
        return true;
    }
};