X of a Kind in a Deck of Cards

<-E 914> X of a Kind in a Deck of Cards

class Solution {
public:
    bool hasGroupsSizeX(vector<int>& deck) {
        unordered_map<int, int> mp;
        for(auto d : deck)
            mp[d]++;
        int x;
        x = mp.begin()->second;
        for(auto it : mp)
            x = gcd(x, it.second);
        if(x > 1) 
            return true;
        return false;
    }
};