POJ - Cable master （二分搜索）

题意：有N条绳子，他们的长度分别是Li。如果从他们中切割出K条长度相同的绳子的话，这K条绳子每条最长能有多长？答案保留2位小数。（例题）

1 <= 10N, 10K, Li <= 1000000

http://poj.org/problem?id=1064

思路：假定一个解并判断是否可行。

#include <iostream>  #include <cstdio>  #include <cmath>using namespace std;  const int MAX_N = 10000, INF = 100000+1;  int N, K;  double a[MAX_N+1];bool C(double x){int num = 0;for(int i = 0; i < N; i++)num += (int)(a[i] / x);return num >= K;}void solve(){double l = 0, r = INF;for(int i = 0; i < 100; i++){double mid = (l+r) / 2;if(C(mid))l = mid;elser = mid;}//printf("%lf\n", r);printf("%.2lf\n", floor(l*100)/100);}int main()  {  //freopen("in.txt", "r", stdin);   scanf("%d %d", &N, &K);for(int i = 0; i < N; i++)scanf("%lf", a+i);solve();return 0;  }