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Description
Peter has just learned mathematics. He learned how to add, and how to multiply. The fact that 2 + 2 = 2 × 2 has amazed him greatly. Now he wants find more such examples. Peters calls a collection of numbers beautiful if the product of the numbers in it is equal to their sum.
For example, the collections {2, 2}, {5}, {1, 2, 3} are beautiful, but {2, 3} is not.
Given n, Peter wants to find the number of beautiful collections with n numbers. Help him!
Input
Output
Sample Input
2 5
Sample Output
1 3
Hint
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<vector>
#include<stack>
using namespace std;
int n,ans;
void dfs(int x,int k,int product,int sum)
{
for(int i=x;i>=2;i--)
{
if(product*i>sum+i+n-k) continue;
else if(product*i==sum+i+n-k) ans++;
else dfs(i,k+1,product*i,sum+i);
}
}
int main()
{
scanf("%d",&n);
dfs(n,1,1,0);
printf("%d\n",ans);
return 0;
}
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原文地址：http://www.cnblogs.com/a972290869/p/4433959.html
