poj1064 Cable master（二分查找）

https://vjudge.net/problem/POJ-1064

二分就相当于不停地折半试。

C++AC，G++WA不知为何，有人说C函数ans那里爆int了，改了之后也没什么用。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<queue>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<cmath>
 7 #include<map>
 8 #define lson l, m, rt<<1
 9 #define rson m+1, r, rt<<1|1
10 #define INF 0x3f3f3f3f
11 typedef unsigned long long ll;
12 using namespace std;
13 int n, m;
14 double L[10010], sum=0;
15 int C(double x)//x为每条边长度 
16 {
17     int ans = 0;
18     for(int i = 0; i < n; i++){
19         ans += (int)(L[i]/x); 
20     }
21     if(ans < m) return 0;
22     return 1;
23 }
24 int main()
25 {
26     cin >> n >> m;
27     for(int i = 0; i < n; i++){
28         cin >> L[i];
29         sum += L[i];
30     }
31     sum = sum/m+1;
32     double lb = 0, ub = sum;//ub也可以直接等于INF 
33     for(int i = 0; i < 100; i++){
34         double mid = (lb+ub)/2;
35         if(C(mid)){
36             lb = mid;
37         } 
38         else ub = mid;
39     }
40     printf("%.2lf\n", floor(ub*100)/100); 
41     return 0;
42 }