poj 1276 Cash Machine（多重背包…

题意：有一个Cash
Machine，里面装有n种面值为n[i]的货币，每种有v[i]张。问在所换金额不超过cash元钱的情况下，所能换取的最大金额。

思路：原版多重背包模版，直接用就行，不理解的看一多重背包的讲解（很详细）

//556K
47MS

#include <stdio.h>

#include <string.h>

#define M 100010

#define N 15

int dp[M],count
,val
;

int money;

int max (int a,int b)

{

return a
> b ? a : b;

}

void MulPack (int cost,int amount)

{

int v
;

if
(cost*amount >=
money)
//完全背包

{

for (v = cost;v <= money;v ++)

dp[v] = max (dp[v],dp[v-cost] + cost);

return ;

}

int k =
1;

while (k
< amount)

{

for (v = money;v >= k*cost;v
--) //分解成多个0/1背包

dp[v] = max (dp[v],dp[v-k*cost] + k*cost);

amount -= k;

k *= 2;

}

for (v =
money;v >= amount*cost;v --)

dp[v] = max (dp[v],dp[v-amount*cost] + amount*cost);

}

int main ()

{

int
n,i;

while
(~scanf ("%d%d",&money,&n))

{

memset (dp,0,sizeof(dp));

for (i = 0;i < n;i ++)

scanf
("%d%d",&count[i],&val[i]);

for (i = 0;i < n;i ++)

MulPack(val[i],count[i]);

printf ("%d\n",dp[money]);

}

}