hdu 2126 Buy the souvenirs（求方案数的背包）

推荐链接http://blog.csdn.net/zizaimengzhongyue/article/details/9332121

把排序的位置放错了，一直WA，不太细心

f[i][j]含义： i 元可以买 j 种物品的方案数，方案数f[i]=f[i]+f[i-a[i]]，很容易得到  f[i][j]=f[i][j]+f[i-a[i][j];

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int cmp(const void *a,const void *b)
{
    return *(int *)a-*(int *)b;
}
int main()
{
    int t,n,m,i,j,k;
    int a[35],f[505][35];
    scanf("%d",&t);
    while(t--)
    {
        int tt;
        scanf("%d%d",&n,&m);
        int sum=0;
        tt=0;
        for(i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
            
        }
        qsort(a+1,n,sizeof(a[0]),cmp);
        for(i=1;i<=n;i++)
        {
        sum+=a[i];
            if(sum<=m)
                tt=i;
        }
        if(sum<=m)
        {
            printf("You have 1 selection(s) to buy with %d kind(s) of souvenirs.
",n);
            continue;
        }
        if(a[1]>m)
        {
            printf("Sorry, you can't buy anything.
");
            continue;
        }
        memset(f,0,sizeof(f));
      for(i=0;i<=m;i++)
          f[i][0]=1;
        for(i=1;i<=n;i++)
        {
            for(j=m;j>=a[i];j--)
            {    
             for(k=tt;k>=1;k--)
                    f[j][k]=f[j][k]+f[j-a[i]][k-1];
            }
        }
        if(f[m][tt]==0)
            printf("Sorry, you can't buy anything.
");
          else
            printf("You have %d selection(s) to buy with %d kind(s) of souvenirs.
",f[m][tt],tt);
    
    }
    return 0;
}