#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 10010;
int a[N];
int n, m;
bool check(int x)
{
    int cnt = 0;
    for (int i = 0; i < n; i++)
        cnt += a[i] / x;
    return cnt <= m;
}
int main()
{
    cin >> n >> m;
    for (int i = 0; i < n; i++)
    {
        double x;
        cin >> x;
        a[i] = (int)(x * 100.0);
    }
    int l = 0, r = 10000000;
    while (l < r)
    {
        int mid = l + r >> 1;
        if (check(mid))
            r = mid;
        else
            l = mid + 1;
    }
    printf("%.2lf", l * 1.0 / 100);
    return 0;
}

上述代码只能得35分

把check函数中的return cnt <= m 改成 return cnt >= m 然后主函数中的条件判断也对应修改 l = mid, r = mid - 1,就能AC？ 为什么？