242. Valid Anagram

https://leetcode.com/problems/valid-anagram/

1. Use hashmap:

//48 ms    7.2 MB
class Solution {
public:
    bool isAnagram(string s, string t) {
        if(s.length() != t.length())
            return false;
        map<char, int> s_letters;
        for(int i = 0; i<s.length(); i++){
            s_letters[s[i]] += 1;
        }
        for(int i = 0; i<s.length(); i++){
            s_letters[t[i]] -= 1;
        }
        for(map<char, int>::iterator it = s_letters.begin(); 
            it != s_letters.end(); it++){
            if(it->second!=0){
                return false;
            }
        }
        return true;
    }
};

2. Use STL sort():

//72 ms    7.2 MB
class Solution {
public:
    bool isAnagram(string s, string t) {
        if(s.size() != t.size()) return false;
        sort(s.begin(), s.end());
        sort(t.begin(), t.end());
        return s==t;
    }
};