leetcode1921.消灭怪物的最大数量（中等）

解法：排序+贪心
具体：计算出每个怪物到达城市的时间，然后排序。

class Solution {
public:
    int eliminateMaximum(vector<int>& dist, vector<int>& speed) {
        
        int n = dist.size();
        vector<double> time(n);
        for (int i = 0; i < n; ++i) {
            time[i] = (double)dist[i] / (double)speed[i];
        }
        sort(time.begin(), time.end());
        for (int i = 0; i < n; ++i) {
            if (time[i] <= i) return i;
        }
        return n;
    }
};