poj1276 Cash Machine(多重背包)

题目点我点我点我

题意:给你一个cash,然后有N种价值为D,数量为n的钱币,要求凑出最接近cash的价值。
多重背包。

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <algorithm>
using namespace std;
int v;
int dp[100100];

void ZeroOnePack(int cost,int weight)
{
    for(int i=v;i>=cost;i--)
        dp[i]=max(dp[i],dp[i-cost]+weight);
}

void CompletePack(int cost,int weight)
{
    for(int i=cost;i<=v;i++)
        dp[i]=max(dp[i],dp[i-cost]+weight);
}

void MultipliesPack(int cost,int weight,int amount)
{
    if(cost*amount>=v)CompletePack(cost,weight);
    else
    {
        for(int k=1;k<amount;)
        {
            ZeroOnePack(k*cost,k*weight);
            amount-=k;
            k<<=1;
        }
        ZeroOnePack(amount*cost,amount*weight);
    }
}

int main()
{
    int cash,N,n,d;
    while(~scanf("%d",&cash))
    {
        memset(dp,0,sizeof(dp));
        v=cash;
        scanf("%d",&N);
        if(N==0)
        {
            printf("0\n");
            continue;
        }
        for(int i=1;i<=N;i++)
        {
            scanf("%d%d",&n,&d);
            MultipliesPack(d,d,n);
        }
        printf("%d\n",dp[v]);

    }
    return 0;
}

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