843A - Sorting by Subsequences

843A - Sorting by Subsequences

还好之前了解过一点白书上的permutation！

我写的递归，其实很容易直接写成递推啊

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 const int maxn=1e5+10;
 4
 5 int nex[maxn];
 6 struct Node{
 7     int id,x;
 8     bool operator<(const Node &a)const {
 9         return x<a.x;
10     }
11 }p[maxn];
12 int vis[maxn];
13 vector<int> v[maxn];
14 void dfs(int u){
15     vis[u]=1;
16     v[res].push_back(u);
17     if(!vis[nex[u]]) dfs(nex[u]);
18 }
19 int main(){
20     int n;
21     while(scanf("%d",&n)!=EOF){
22         for(int i=0;i<=n;i++) v[i].clear();
23         for(int i=1;i<=n;i++){
24             scanf("%d",&p[i].x);
25             p[i].id=i;
26         }
27         sort(p+1,p+n+1);
28         for(int i=1;i<=n;i++){
29             nex[i]=p[i].id;
30         }
31         memset(vis,0,sizeof(vis));
32         for(int i=1;i<=n;i++) if(!vis[i]){
33             dfs(i);
34         }
35         printf("%d\n",res);
36         for(int i=0;i<res;i++){
37             printf("%d",v[i].size());
38             for(int j=0;j<v[i].size();j++) printf(" %d",v[i][j]);
39             puts("");
40         }
41     }
42 }

tourist~~

 1 #include <bits/stdc++.h>
 2
 3 using namespace std;
 4
 5 const int N = 1234567;
 6
 7 pair <int, int> a[N];
 8 int p[N];
 9 bool was[N];
10
11 int main() {
12   int n;
13   scanf("%d", &n);
14   for (int i = 0; i < n; i++) {
15     scanf("%d", &a[i].first);
16     a[i].second = i;
17   }
18   sort(a, a + n);
19   for (int i = 0; i < n; i++) {
20     p[i] = a[i].second;
21   }
22   vector < vector <int> > res;
23   for (int i = 0; i < n; i++) {
24     if (was[i]) {
25       continue;
26     }
27     int x = i;
28     vector <int> cycle;
29     while (!was[x]) {
30       was[x] = true;
31       cycle.push_back(x);
32       x = p[x];
33     }
34     res.push_back(cycle);
35   }
36   int cnt = res.size();
37   printf("%d\n", cnt);
38   for (int i = 0; i < cnt; i++) {
39     int cc = res[i].size();
40     printf("%d", cc);
41     for (int j = 0; j < cc; j++) {
42       printf(" %d", res[i][j] + 1);
43     }
44     printf("\n");
45   }
46   return 0;
47 }

tourist