poj 1276 多重背包 解题报告

Cash Machine

Time Limit: 1000MS Memory Limit: 10000K
Total Submissions: 35336 Accepted: 12799
Description

A Bank plans to install a machine for cash withdrawal. The machine is able to deliver appropriate @ bills for a requested cash amount. The machine uses exactly N distinct bill denominations, say Dk, k=1,N, and for each denomination Dk the machine has a supply of nk bills. For example,

N=3, n1=10, D1=100, n2=4, D2=50, n3=5, D3=10

means the machine has a supply of 10 bills of @100 each, 4 bills of @50 each, and 5 bills of @10 each.

Call cash the requested amount of cash the machine should deliver and write a program that computes the maximum amount of cash less than or equal to cash that can be effectively delivered according to the available bill supply of the machine.

Notes:
@ is the symbol of the currency delivered by the machine. For instance, @ may stand for dollar, euro, pound etc.

题解：

多重背包。

代码：

#include<cstdio>#include<iostream>#include<cstring>#include<algorithm>#include<cmath>#include<vector> using namespace std; struct node{    int n,v;}a[20];const int N=100000+10; int dp[N],maxn=0,tem,sum,n;  int main()  {      while(~scanf("%d%d",&sum,&n))      {          for(int i=1;i<=n;i++)          scanf("%d%d",&a[i].n,&a[i].v);          if (!sum||!n)        {            printf("0\n");            continue;        }         memset(dp,0,sizeof(dp));          dp[0]=1;        maxn=0;          for(int i=1;i<=n;i++)        for(int j=maxn;j>=0;j--)          {              if(dp[j])              {                  for (int k=1;k<=a[i].n;k++)                {                    tem=j+k*a[i].v;                    if(tem>sum) continue;                    dp[tem]=1;                    if (tem>maxn) maxn=tem;                }            }          }          printf("%d\n",maxn);      }    return 0;  }