poj 1276 完全背包

poj 1276
Cash MachineTime Limit: 1000MS
Memory Limit: 10000KTotal Submissions: 18242
Accepted: 6364

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. 

Input

The program input is from standard input. Each data set in the input stands for a particular transaction and has the format: 
cash N n1 D1 n2 D2 ... nN DN 
where 0 <= cash <= 100000 is the amount of cash requested, 0 <=N <= 10 is the number of bill denominations and 0 <= nk <= 1000 is the number of available bills for the Dk denomination, 1 <= Dk <= 1000, k=1,N. White spaces can occur freely between the numbers in the input. The input data are correct. 

Output

For each set of data the program prints the result to the standard output on a separate line as shown in the examples below. 

Sample Input

735 3 4 125 6 5 3 350633 4 500 30 6 100 1 5 0 1735 00 3 10 100 10 50 10 10

Sample Output

73563000

Hint

The first data set designates a transaction where the amount of cash requested is @735. The machine contains 3 bill denominations: 4 bills of @125, 6 bills of @5, and 3 bills of @350. The machine can deliver the exact amount of requested cash. 
In the second case the bill supply of the machine does not fit the exact amount of cash requested. The maximum cash that can be delivered is @630. Notice that there can be several possibilities to combine the bills in the machine for matching the delivered cash. 
In the third case the machine is empty and no cash is delivered. In the fourth case the amount of cash requested is @0 and, therefore, the machine delivers no cash.

Source

Southeastern Europe 2002

 

Run IDUserProblemResultMemoryTimeLanguageCode LengthSubmit Time9848681guzhoudiaoke1276Accepted776K47MSG++1118B2012-02-25 17:32:579308589guzhoudiaoke1276Accepted780K579MSGCC827B2011-09-12 23:52:36

 

1) 579MS

/*
 * poj 1276
 * guzhoudiaoke@126.com
 * 2011-09-12
 */
#include <stdio.h>
#include <string.h>
#define MAX    100000
int dp[MAX+1];
int main()
{
    int cash, N, i, j, k, nk[11], dk[11];
    
    while (scanf("%d%d", &cash, &N) != EOF)
    {
        for (i = 1; i <= N; i++)
            scanf("%d%d", &nk[i], &dk[i]);
        
        if (cash == 0 || N == 0) {
            printf("0\n");
            continue;
        }
        
        memset(dp, 0, sizeof(dp));
        dp[0] = 1;
        
        int found = 0;
        for (i = 1; i <= N && !found; i++)
            for (j = cash; j >= 0 && !found; j--)
                if (dp[j] == 1)
                    for (k = 1; k <= nk[i] && j+dk[i]*k <= cash; k++)
                    {
                        dp[j + dk[i]*k] = 1;
                        if (j + dk[i]*k == cash) 
                            found = true;
                    }
        
        int i = cash;
        while (dp[i] == 0)
            i--;
        printf("%d\n", i);
    }
    
    return 0;
}

 

 

2)47MS

/*
 * poj 1276
 * 采用更类似多重背包的方法
 * 孤舟钓客
 * 2012-02-25 16：22
 */
 
#include <stdio.h>
#include <string.h>
#define MAX 100000
int dp[MAX+1];
int inline max(int a, int b)
{
    return a > b ? a : b;
}
void solve(int cash, int N, int nk[], int dk[])
{
    int i, j, k;
    for (i = 1; i <= N; i++) {
        if (dk[i] * nk[i] >= cash) {    /* 该物品总数超过容量， 完全背包 */
            for (j = dk[i]; j <= cash; j++)
                dp[j] = max(dp[j], dp[j-dk[i]]+dk[i]);
        }
        else {    /* 多重背包 */
            k = 1;
            while (k < nk[i]) {
                for (j = cash; j >= k*dk[i]; j--)
                    dp[j] = max(dp[j], dp[j-dk[i]*k] + dk[i]*k);
                nk[i] -= k;
                k *= 2;
            }
            for (j = cash; j >= nk[i]*dk[i]; j--)
                dp[j] = max(dp[j], dp[j-dk[i]*nk[i]] + dk[i]*nk[i]);
        }
    }
}
int main()
{
    int cash, N, i, j, k, nk[11], dk[11], found, t;
    
    while (scanf("%d%d", &cash, &N) != EOF)
    {
        for (i = 1; i <= N; i++)
            scanf("%d%d", &nk[i], &dk[i]);
            
        if (cash == 0 || N == 0) {
            printf("0\n");
            continue;
        }
        
        memset(dp, 0, sizeof(dp));
        
        solve(cash, N, nk, dk);
        
        printf("%d\n", dp[cash]);
    }
    
    return 0;
}