POJ 2245

//此题一看便是简单的回溯题用DFS+回溯便可以做出来了、
#include <iostream>
#define MAXN 20
using namespace std;

int _m[MAXN];
int out[6];

int index;

void DFS(int time);

int n;

int main()
{
    //freopen("acm.acm","r",stdin);
    
    int i;
    while(cin>>n,n)
    {
        for(i = 0; i < n; ++ i)
        {
            cin>>_m[i];
        }
        index = 0;
        DFS(0);
        cout<<endl;
    }
}

void DFS(int time)
{
    if(index == 6)
    {
        int i;
        for(i = 0; i < index; ++ i)
        {
            cout<<out[i]<<" ";
        }
        cout<<endl;
        return;
    }
    if(n - time + index < 6)
    {
        return;
    }
    
    out[index ++] = _m[time];
    DFS(time+1);
    -- index;
    DFS(time+1);
}