题解（不过大家为什么都抄练习记录？）

#include<bits/stdc++.h>
using namespace std;
int a[1000005];
long long n,k;

bool check(long long mid){
    long long sum = 0;
    for(int i = 0;i < n;i ++){
        sum += a[i] / mid;
    }
    if(sum >= k){
        return true;
    } else {
        return false;
    }
}

int main(){
    int max = 0;
    long long g = 0;
    double x;
    cin >> n >> k;
    for(int i = 0;i < n;i ++){
        cin >> x;
        a[i] = x * 100;
        if(a[i] > max){
            max = a[i];
        }
        g += a[i];
    }
    long long l = 1,r = max,mid,ans = 0;
    if(g < k){
        cout << 0;
        return 0;
    }
    while(l <= r){
        mid = (l + r) / 2;
        if(check(mid)){
            l = mid + 1;
            ans = mid;
        } else {
            r = mid - 1;
        }
    }
    double ans1 = ans / 100.0;
    printf("%.2f",ans1);
    return 0;
}