數組中出現次數超過一半的數字

class Solution {
public:
	int MoreThanHalfNum_Solution(vector<int> numbers) {
		if(numbers.size() == 0)
            return 0;
       	map<int,int> m;
        for(int i = 0; i < numbers.size(); i++){
            if(m[numbers[i]] != NULL)
            	m[numbers[i]]++;
            else
                m[numbers[i]] = 1;
            if(m[numbers[i]] * 2 > numbers.size())
                return numbers[i];
        }
        return 0;
	}
};