从全排列看递归

#include <iostream>
#include <cstdlib>
using namespace std;

template <class T>
void print(T*p,int num)
{
    for(int i = 0;i < num;i++)
    {
        cout<<p[i]<<" ";
    }
    cout<<endl;
}

template <class T>
void permutations(T *p,int first,int last)
{
    if(first == last)   //当first = last，p[first:last]只有一个全排列
       print(p,last+1);
    else{               // p[first:last] 有多于一个排列，递归生成这些排列
        for(int i = first;i <= last;i++)
        {
            swap(p[i],p[first]);
            permutations(p,first+1,last);
            swap(p[i],p[first]);
        }
    }

}


int main()
{
    cout << "please enter the numbers!" << endl;
    char num;
    int countNum = 0;
    char arrayNum[1000];
    while(cin >> num && num != ‘0‘)
    {
        arrayNum[countNum] = num;
        countNum++;
    }
    cout<<endl;
    permutations(arrayNum,0,countNum-1);
    return 0;
}