PKU 1064 Cable Master

２分探索

#include<iostream>
#include<cstdio>
#include<math.h>
using namespace std;

int n,k;
double l[10000];
bool C(double x){
	int cnt = 0;
	for(int i = 0; i < n;i++){
		cnt += (int)(l[i] / x);
	}
	return cnt >= k;
}

int main(){
	scanf("%d %d",&n,&k);
	for(int i = 0; i < n; i++){
		scanf("%lf", &l[i]);
	}
	double lb = 0, ub = INT_MAX;

	for(int i = 0; i < 100; i++){
		double mid = (lb + ub) / 2;
		if(C(mid)) lb = mid;
		else ub = mid;
	}
	printf("%.2f\n", floor(ub * 100) / 100);
	return 0;
}