NYOJ 914 maximize Yougth

Yougth maximum time limit: 1000 MS | memory limit: 65535 KB difficulty: 4

Description

The weight and value of n items in Yougth are Wi and Vi. Can you help him select k items to maximize the value of unit weight?

Input

Multiple groups of test data
The first row of each group of test data has two numbers n and k, and the next row has n numbers Wi and Vi.
(1 <= k = n <= 10000) (1 <= Wi, Vi <= 1000000)

Output

Outputs the maximum unit value. (Retain two decimal places)

Sample Input

3 22 25 32 1

Sample output

0.75

Idea: Binary and greedy
#include
       
        #include
        
         #includeusing namespace std;int w[10000],v[10000],n,k;double y[10000];bool C(double x){ for(int i=0;i
         
          =0;}void solve(){            double lb =0,ub=10000;            for(int i=0;i<100;i++)            {               double mid =(lb+ub)/2;               if(C(mid)) lb = mid;               else ub=mid;            }            printf("%.2f\n",ub);}int main(){      while(cin>>n>>k)    {   for(int i=0;i
          
           >w[i]>>v[i];   solve();   //system("pause");    }   return 0;   }