[AcWing 823] 排列

#include

using namespace std;
const int N = 10;
int n;
void dfs(int u, int nums[], bool st[]) {
    if (u > n) {
        for (int i = 1; i <= n; i++)    cout << nums[i] << ' ';
        cout << endl;
    }
    else {
        for (int i = 1; i <= n; i++)
            if (!st[i]) {
                st[i] = true;
                nums[u] = i;
                dfs(u + 1, nums, st);
                st[i] = false;
            }
    }
}
int main()
{
    cin >> n;
    int nums[N];
    bool st[N] = {0};
    dfs(1, nums, st);
    return 0;
}