algo-aha

森林中的兔子数

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

某些兔子将告诉你多少兔子和它同色，问总共最少有多少兔子？

int numRabbits(vector<int>& answers) {
    // 数x每组有x+1个，共有ceil(count[x]/(x+1)) = (count[x]+x)/(x+1)组，
    // 所以报数x的兔子数为 (count[x]+x)/(x+1)*(x+1)
    unordered_map<int, int> count;
    for (int num : answers) count[num]++;

    int ans = 0;
    for (auto &e : count) {
        int x = e.first;
        ans += (count[x] + x) / (x + 1) * (x + 1);
    }
    return ans;
}