poj1276 多重背包

背包问题，建议先看看背包九讲，然后这道题就能水之。。。

这是我整理背包九讲里的模板，有基础的可以看看，大牛就不要来鄙视我这个小菜了。。。

//01背包
procedure ZeroOnePack(cost,weight)
    for v=V..cost
        f[v]=max{f[v],f[v-cost]+weight}
for i=1..N
    ZeroOnePack(c[i],w[i]);

//完全背包
procedure CompletePack(cost,weight)
    for v=cost..V
        f[v]=max{f[v],f[v-c[i]]+w[i]}
for i=1..N
    CompletePack(cost,weight);

//多重背包
procedure MultiplePack(cost,weight,amount)
    if cost*amount>=V
        CompletePack(cost,weight)
        return
    integer k=1
    while k<amount
        ZeroOnePack(k*cost,k*weight)
        amount=amount-k
        k=k*2
    ZeroOnePack(amount*cost,amount*weight)
for i=1..N
    MultiplePack(cost,weight,amount);

#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#define MAX 100111
using namespace std;
int cash,N;
int n[20],d[20];
int f[MAX];
void ZeroOnePack(int cost,int weight)
{
    for(int v=cash;v>=cost;v--)
        f[v]=max(f[v],f[v-cost]+weight);
    //cout<<f[cash]<<endl;
}
void CompletePack(int cost,int weight)
{
    for(int v=cost;v<=cash;v++)
       f[v]=max(f[v],f[v-cost]+weight);
    //cout<<f[cash]<<endl;
}
void MultiplePack(int cost,int weight,int amount)
{
    if (cost*amount>=cash)
    {
       CompletePack(cost,weight);
       return ;
    }
    int k=1;
    while (k<amount)
    {
        ZeroOnePack(k*cost,k*weight);
        amount=amount-k;
        k=k*2;
    }
    ZeroOnePack(amount*cost,amount*weight);
}
int main()
{
    int i;
    while(cin>>cash>>N)
    {
        for(i=1;i<=N;i++)
            cin>>n[i]>>d[i];
        memset(f,0,sizeof(f));
        for(i=1;i<=N;i++)
        {
            MultiplePack(d[i],d[i],n[i]);
        }
        for(i=cash;i>=0;i--)
            if(f[i]==i)
             {cout<<f[i]<<endl;break;}
    }
}