hdu 1171Big Event in HDU

http://acm.hdu.edu.cn/showproblem.php?pid=1171

#include<stdio.h>
#include<string.h>
#define max(x,y) x>y?x:y 
int main()
{
    int n;
    int m;
    int sum;
    int i,j,jj;
    int a[55];
    int w[5500];
    int f[250000];
    while(~scanf("%d",&n)&&n>0)
    {
        memset(f,0,sizeof(f));
        jj=0;
        sum=0;
        for(i=0;i<n;i++)
        {
            
            scanf("%d%d",&a[i],&m);
            for(j=0;j<m;j++)
            {
                sum+=a[i];
                w[jj++]=a[i];
            }
            
        }
        for(i=0;i<jj;i++)
        {
            for(j=sum/2;j>=w[i];j--)
            {
                f[j]=max(f[j],f[j-w[i]]+w[i]);
            }
        }
        printf("%d %d\n",sum-f[sum/2],f[sum/2]);
    }
}