[哈希] leetcode 781 Rabbits in Forest

problem:https://leetcode.com/problems/rabbits-in-forest/

        值为n的可以和其它n + 1个值为n的成组，统计每个值出现的次数，看它们可以组成多少组相同颜色的兔子，然后乘以组中兔子个数。

class Solution {
public:
    int numRabbits(vector<int>& answers) {
        unordered_map<int,int> counts;
        for(int i = 0; i < answers.size(); i++)
        {
            counts[answers[i]]++;
        }
        int res = 0;
        for(auto& count : counts)
        {
            int expect = count.first + 1;
            int number = count.second;
            res += ceil((float)number / expect) * expect;
        }
        return res;
    }
};