poj 2392 Space Elevator （多重背包）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
struct Class{
    int h,maxh,c;
}a[405];
int cmp(Class x,Class y)
{
    return x.maxh<y.maxh;
}
int main()
{
    int n,ans,i,j,dp[40005],sum[40005];
    while(cin>>n)
    {
        for( i=0;i<n;i++)
            cin>>a[i].h>>a[i].maxh>>a[i].c;

        sort(a,a+n,cmp);
        memset(dp,0,sizeof(dp));
        dp[0]=1;
        int ans=0;
        for(i=0;i<n;i++)
        {
            memset(sum,0,sizeof(sum));
            for(j=a[i].h;j<=a[i].maxh;j++)
            {
                if(!dp[j]&&dp[j-a[i].h]&&sum[j-a[i].h]<a[i].c)
                {
                    dp[j]=1;
                sum[j]=sum[j-a[i].h]+1;//统计石块放置的个数
                if(ans<j)
                ans=j;

                }
            }
        }
        cout<<ans<<endl;

    }

    return 0;
}