排列組合-Sucessful

#include <iostream>
#include <cstdlib>

using namespace std;
void perm(int *ch,int a,int b);

    int n;
    int c=0;

int main()
{
    cout << "enter a number you want to perm : "<<endl;
    cin >> n;
    int list[n];
    for(int i=0;i<n;i++)
        list[i] = i+1;

    perm(list,0,n-1);
    cout << c <<" type for " << n << " permutation"<<endl;
    system("pause");
    return 0;
}


void perm(int *ch,int a,int b)
{
     if(a==b){
        for(int i=0;i<n;i++)
            cout << ch[i];
        cout << endl;
        c++;
     }
     else
        for(int j=a;j<n;j++){
            swap(ch[a],ch[j]);
            perm(ch,a+1,b);
            swap(ch[a],ch[j]);
        }
}