dfs

#include <iostream>

using namespace std;

const int N = 10;//存1-9的数

int n;

void dfs(int u,int nums[],bool st[])
{
    if(u > n)//边界条件
    {
        for (int i = 1; i <= n;i ++)
            cout << nums[i] << " ";
        cout << endl;
    }
    else 
    {
        for (int i = 1; i <= n;i ++)//循环条件
        {
            if(!st[i])
            {
                st[i] = true;
                nums[u] = i;
                dfs(u + 1, nums, st);
                st[i] = false;//恢复现场
            }
        }
    }
}
int main()
{
    cin >> n;

    int nums[N];//整数数组
    bool st[N] = {0};//判断数组

    dfs(1,nums,st);

}