poj 1064 Cable master 二分

地址 http://poj.org/problem?id=1064

 题解 二分即可

其实 对于输入与精度计算不是很在行  

老是被卡精度

后来学习了一个函数 floor 向负无穷取整 才能ac

代码如下

 1 #include <iostream>
 2 #include <vector>
 3 #include <math.h>
 4 #include <algorithm>
 5 
 6 using namespace std;
 7 
 8 vector<double> v;
 9 
10 int n, k;
11 
12 
13 bool check(double m)
14 {
15     int count = 0;
16     for (int i = 0; i < v.size(); i++)
17     {
18         int cut = v[i] / m;
19         count += cut;
20     }
21 
22     if (count >= k) return false;
23 
24     return true;
25 }
26 
27 
28 int main()
29 {
30     scanf("%d %d",&n,&k);
31 
32     for (int i = 0; i < n; i++) {
33         double t;
34         scanf("%lf",&t);
35         v.push_back(t);
36     }
37 
38     sort(v.begin(),v.end());
39 
40     double l = 0.001; double r = v.back();
41 
42     for (int i = 0; i < 1000; i++) {
43         double mid = (l + r) / 2;
44         if (check(mid)) r = mid;
45         else l = mid + 0.0001;
46     }
47 
48     printf("%.2f", floor(l*100)/100);
49     return 0;
50 }

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