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

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true
Example 2:

Input: s = "rat", t = "car"
Output: false
Note:
You may assume the string contains only lowercase alphabets.

Follow up:
What if the inputs contain unicode characters? How would you adapt your solution to such case?

我的答案：hash table （multiset慢好幾倍）

class Solution {
public:
    bool isAnagram(string s, string t) {
        int len_s = s.size();
        int len_t = t.size();
        if (len_s != len_t)
            return false;
        
        unordered_map<char, int> map_s;
        unordered_map<char, int> map_t;
        
        for (int i=0; i<len_s; ++i) {
            char c_s = s[i];
            char c_t = t[i];
            
            if (map_s.find(c_s) == map_s.end())
                map_s[c_s] = 1;
            else
                ++map_s[c_s];
            
            if (map_t.find(c_t) == map_t.end())
                map_t[c_t] = 1;
            else
                ++map_t[c_t];
        }
        
        for (const auto& p_s : map_s) {
            if ( p_s.second != map_t[p_s.first] ) {
                return false;
            }
        }
        
        return true;
    }
};

Runtime: 28 ms, faster than 44.13% of C++ online submissions for Valid Anagram.
Memory Usage: 7.7 MB, less than 22.42% of C++ online submissions for Valid Anagram.

看答案：
https://leetcode.com/problems/valid-anagram/solution/
確實用hash table比較快，但是這邊不用2個hash table，只用一個，然后加減就可以了，想到229這道題
https://leetcode.com/problems/majority-element-ii/discuss/63520/Boyer-Moore-Majority-Vote-algorithm-and-my-elaboration
Boyer-Moore Majority Vote algorithm