二分搜索 POJ 1064 Cable master

题目传送门

/*
    题意：n条绳子问切割k条长度相等的最长长度
    二分搜索：搜索长度，判断能否有k条长度相等的绳子
*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

const int MAXN = 1e4 + 10;
const int INF = 0x3f3f3f3f;
double w[MAXN];
int n, k;

int check(double len)   {
    int ret = 0;
    for (int i=1; i<=n; ++i)    {
        ret += (int) (w[i] / len);
    }
    return ret;
}

int main(void)  {       //POJ 1064 Cable master
    //freopen ("POJ_1064.in", "r", stdin);
    
    while (scanf ("%d%d", &n, &k) == 2) {
        for (int i=1; i<=n; ++i)    {
            scanf ("%lf", &w[i]);
        }
        double l = 0, r = 1e9;
        for (int i=1; i<=100; ++i)  {
            double mid = (l + r) / 2;
            if (check (mid) >= k)   l = mid;
            else    r = mid;
        }
        printf ("%.2f
", floor (l * 100) / 100);
    }

    return 0;
}