Minimum Scalar Product May 21, 2010

GOOGLE CODE JAM 2008
Round 1A 2008
AC for both Smaller and Bigger Data

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<algorithm>

using namespace std;
int main()
{
  FILE *p=fopen("a.txt","w");
  FILE *in=fopen("A-large-practice.in","r");
  long long int t,n,i,j,k;
  long long int x[10000];
  long long int y[10000];
  long long int total;
  long long int c=0;
  fscanf(in,"%lld",&t);
  while(t--){
    fscanf(in,"%lld",&n);
    for(i=0;i<n;i++)
      fscanf(in,"%lld",&x[i]);
    for(i=0;i<n;i++)
      fscanf(in,"%lld",&y[i]);

    sort(x,x+n);
    sort(y,y+n);
    total=0;
    for(i=0,j=n-1;i<n;i++,j--)
      total+=(long long int )(x[i]*y[j]);
    fprintf(p,"Case #%lld: %lld\n",++c,total);
   }
  fclose(p);
  fclose(in);
return 0;
}