I NEED A OFFER!---hdu1203(01背包)

#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<queue>

using namespace std;

#define N 50000
int a[N],dp[N];
int main()
{
    int n,m,c[N];
    double w[N],dp[N];
    while(scanf("%d %d",&n,&m),n+m)
    {
        for(int i=1;i<=m;i++)
        {
            scanf("%d %lf",&c[i],&w[i]);
        }
        memset(dp,0,sizeof(dp));
        for(int i=1;i<=m;i++)
        {
            for(int j=n;j>=c[i];j--)
            {
                dp[j]=max(dp[j],(1-(1-dp[j-c[i]])*(1-w[i])));
            }
        }
        printf("%.1lf%%\n",dp[n]*100);
    }
    return 0;
}