整数集合

#include<bits/stdc++.h>
using namespace std;
int num=0,a[10001]={0},n,r;
bool b[10001]={0};
int search(int);
int print();
int main()
{
cin>>n>>r;
search(1);
cout<<num<<endl;
}
int search(int k)
{
for (int i=1;i<=n;i++)
if (!b[i])
{
a[k]=i;
b[i]=1;
if (k==r) print();
else search(k+1);
b[i]=0;
}
}
int print()
{
num++;
for (int i=1;i<=r;i++)
cout<<a[i]<<" ";
cout<<endl;
}