poj 2392 多重背包

题意：有几个砖，给出高度，能放的最大高度和数目，求这些砖能垒成的最大高度

依据lim排个序，按一层一层进行背包

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
using namespace std;
const int maxn=40005;
int n,m,t;
int dp[maxn];
struct Node
{
    int h,c;
    int l;
    void input()
    {
        scanf("%d%d%d",&h,&l,&c);
    }
}node[maxn];
bool cmp(Node a,Node b)
{
    return a.l<b.l;
}
//0-1背包，代价为cost,获得的价值为weight
void ZeroOnePack(int cost,int weight,int lim)
{
    for(int i=lim;i>=cost;i--)
      dp[i]=max(dp[i],dp[i-cost]+weight);
}

//完全背包，代价为cost,获得的价值为weight
void CompletePack(int cost,int weight,int lim)
{
    for(int i=cost;i<=lim;i++)
      dp[i]=max(dp[i],dp[i-cost]+weight);
}

//多重背包
void MultiplePack(int cost,int weight,int amount,int lim)
{
    if(cost*amount>=lim) CompletePack(cost,weight,lim);
    else
    {
        int k=1;
        while(k<amount)
        {
            ZeroOnePack(k*cost,k*weight,lim);
            amount-=k;
            k<<=1;
        }
        ZeroOnePack(amount*cost,amount*weight,lim);//这个不要忘记了，经常掉了
    }
}
int main()
{
    int i,j,k;
    #ifndef ONLINE_JUDGE
    freopen("1.in","r",stdin);
    #endif
    while(scanf("%d",&n)!=EOF)
    {
        for(i=0;i<n;i++)    node[i].input();
        sort(node,node+n,cmp);
        memset(dp,0,sizeof(dp));
        for(i=0;i<n;i++)
        {
            MultiplePack(node[i].h,node[i].h,node[i].c,node[i].l);
        }
        int maxh=node[n-1].l;
        int ans=0;
        for(i=0;i<=maxh;i++)
        {
            ans=max(dp[i],ans);
        }
        printf("%d",ans);
    }
    return 0;
}