> 如果理解成 价值就是重量，转换成背包问题是ok的。
> 
> 不过我按照“可达性”来理解做题，为什么就不对呢，代码很简单，请好心人帮看一下.
> 
> #include <stdio.h>
> #include <memory.h>
> 
> #define MAX_CASH 100001
> struct Cash
> {
> 	int amount;
> 	int demo;
> };
> 
> int dp[MAX_CASH];
> int used[MAX_CASH];
> 
> Cash allCash[11];
> int nCash;
> int nDeliver;
> 
> int maxCash()
> {
> 	if(nCash == 0 || nDeliver == 0)
> 		return 0;
> 	int i,j,k;
> 	memset(dp, 0, sizeof(dp));
> 	dp[0] = 1;
> 
> 	for( i = 1; i <= nCash; i++)
> 	{
> 		memset(used, 0, sizeof(used));
> 
> 		for( j = allCash[i].demo ; j <= nDeliver; j++)
> 		{
> 			if(dp[j - allCash[i].demo] && 
>  			   used[j - allCash[i].demo] < allCash[i].amount)
> 			{
> 				dp[j] = 1;
> 				used[j] = used[j-allCash[i].demo] + 1;
> 			} 
> 		}
> 	}
> 	
> 	for( i = nDeliver; i >= 0; i--)
> 	{
> 		if(dp[i])
> 		{
> 			return i;
> 		}
> 	}
> 	return 0;
> 
> }
> 
> int main()
> {
> 	while(scanf("%d", &nDeliver) != EOF)
> 	{
> 		scanf("%d", &nCash);
> 		for( int i = 1; i <= nCash; i++)
> 		{
> 			scanf("%d%d", &allCash[i].amount, &allCash[i].demo);
> 		}
> 		printf("%d\n", maxCash());
> 	}
> 	return 0;
> }