poj 2392 Space Elevator(多重バックパック変形)

Space Elevator
Time Limit: 1000MS
 
Memory Limit: 65536K
Total Submissions: 5144
 
Accepted: 2382
Description
The cows are going to space! They plan to achieve orbit by building a sort of space elevator: a giant tower of blocks. They have K (1 <= K <= 400) different types of blocks with which to build the tower. Each block of type i has height h_i (1 <= h_i <= 100) and is available in quantity c_i (1 <= c_i <= 10). Due to possible damage caused by cosmic rays, no part of a block of type i can exceed a maximum altitude a_i (1 <= a_i <= 40000). 
Help the cows build the tallest space elevator possible by stacking blocks on top of each other according to the rules.
Input
* Line 1: A single integer, K 
* Lines 2..K+1: Each line contains three space-separated integers: h_i, a_i, and c_i. Line i+1 describes block type i.
Output
* Line 1: A single integer H, the maximum height of a tower that can be built
Sample Input

3
7 40 3
5 23 8
2 52 6

Sample Output

48

Hint
OUTPUT DETAILS: 
From the bottom: 3 blocks of type 2, below 3 of type 1, below 6 of type 3. Stacking 4 blocks of type 2 and 3 of type 1 is not legal, since the top of the last type 1 block would exceed height 40.
Source
USACO 2005 March Gold
タイトル:http://poj.org/problem?id=2392
分析:この問題は実は多重リュックサックに1つのソートを加えて、まず最高の標高でソートして、それから直接多重リュックサック==
コード:

#include<cstdio>
#include<algorithm>
using namespace std;
const int mm=444;
struct block
{
    int h,a,c;
}g[mm];
bool f[44444];
int i,j,k,n;
bool cmp(block a,block b)
{
    return a.a<b.a;
}
int main()
{
    while(scanf("%d",&n)!=-1)
    {
        for(i=0;i<n;++i)scanf("%d%d%d",&g[i].h,&g[i].a,&g[i].c);
        sort(g,g+n,cmp);
        for(f[0]=1,i=g[n-1].a;i>0;--i)f[i]=0;
        for(i=0;i<n;++i)
            for(j=0;j<g[i].c;++j)
                for(k=g[i].a;k>=g[i].h;--k)
                    f[k]|=f[k-g[i].h];
        for(i=g[n-1].a;i>0;--i)
            if(f[i])break;
        printf("%d
",i);
    }
    return 0;
}