hdu 1171 Big Event in HDU

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

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int a[150005];
struct mes{
    int v,num;
}op[55];
void zeroonepack(int V,int v,int w)
{
    for(int i=V;i>=v;i--)
    a[i]=max(a[i],a[i-v]+w);
}
int main()
{
    int n;
    while(scanf("%d",&n)&&n>0){
        int x,y,j=1,V=0;
        memset(a,0,sizeof(a));
        for(int i=0;i<n;i++){
            scanf("%d%d",&op[i].v,&op[i].num);
            V+=op[i].v*op[i].num;
        }
        for(int i=0;i<n;i++){
            int j=1;
            while(j<=op[i].num){
                zeroonepack(V/2,op[i].v*j,op[i].v*j);
                op[i].num-=j;
                j*=2;
            }
            if(op[i].num>0)
            zeroonepack(V/2,op[i].num*op[i].v,op[i].num*op[i].v);
        }
        printf("%d %d\n",V-a[V/2],a[V/2]);
    }
    return 0;
}