Farmer John goes to Dollar Days at The Cow Store and discovers an unlimited number of tools on sale. During his first visit, the tools are selling variously for $1, $2, and $3. Farmer John has exactly $5 to spend. He can buy 5 tools at $1 each or 1 tool at $3 and an additional 1 tool at $2. Of course, there are other combinations for a total of 5 different ways FJ can spend all his money on tools. Here they are:
1 @ US$3 + 1 @ US$2
1 @ US$3 + 2 @ US$1
1 @ US$2 + 3 @ US$1
2 @ US$2 + 1 @ US$1
5 @ US$1
Write a program than will compute the number of ways FJ can spend N dollars (1 <= N <= 1000) at The Cow Store for tools on sale with a cost of $1..$K (1 <= K <= 100).
Input
A single line with two space-separated integers: N and K.
Output
A single line with a single integer that is the number of unique ways FJ can spend his money.
Sample Input
5 3
Sample Output
5
求k以内的整数组成n有多少种方案
完全背包,注意范围,可以用两个long long拼合
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;
int n,k;
int inf=1;
long long a[1005];
long long b[1005];
int main()
{for(int i=0;i<18;i++)
inf*=10;
scanf("%d%d",&n,&k);
a[0]=1;
for(int i=1;i<=k;i++)
{
for(int j=1;j<=n;j++)
{if(j<i)
continue;
b[j]=b[j]+b[j-i]+(a[j]-a[i])/inf;
a[j]=(a[j]+a[j-i])%inf;}
}
if(b[n])
printf("%I64d",b[n]);
printf("%I64d",a[n]);
return 0;
}