[2019杭电多校第五场][hdu6628]permutation 1

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 const int maxn = 50;
 7 int n, k;
 8 int ans[maxn], vis[maxn];
 9 bool dfs(int id, int l, int r) {
10     if (id == n) {
11         k--;
12         if (!k) {
13             for (int i = 0; i < n; i++)
14                 printf("%d%c", ans[i] - l + 1, i == n - 1 ? ‘\n‘ : ‘ ‘);
15             return 1;
16         }
17         return 0;
18     }
19     for (int i = r - n + 1; i <= l + n - 1; i++) {
20         if (vis[i]) continue; vis[i] = 1; ans[id] = i;
21         if (dfs(id + 1, min(l, i), max(r, i))) {
22             vis[i] = 0;
23             return 1;
24         }
25         vis[i] = 0;
26     }
27     return 0;
28 }
29 int main() {
30     int t;
31     scanf("%d", &t);
32     while (t--) {
33         scanf("%d%d", &n, &k);
34         ans[0] = n; vis[n] = 1;
35         dfs(1, n, n);
36         vis[n] = 0;
37     }
38     return 0;
39 }