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  1. #include <bits/stdc++.h>
  2. #define ll long long
  3. using namespace std;
  4. ll n, a[27], b[27], x[27], dd[27], pa[27], pb[27], res;
  5. void ghinghiem()
  6. {
  7.     bool ok=1;
  8.     for(ll i=1;i<=n && ok;i++) for(ll j=i+1;j<=n;j++){
  9.         ll u=x[i];
  10.         ll v=x[j];
  11.         if( (pa[u] < pa[v]) != (pb[u] < pb[v])){ 
  12.         ok=0; 
  13.         break; 
  14.         }
  15.     }
  16.     if(ok)res++;
  17. }
  18. void backtrack(ll i)
  19. {
  20.     for(ll j=1;j<=n;j++) if(!dd[j]){
  21.         x[i]=j; 
  22.         dd[j]=1;
  23.         if(i==n)ghinghiem(); 
  24.         else backtrack(i+1);
  25.         dd[j]=0;
  26.     }
  27. }
  28. int main()
  29. {
  30.     ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  31.     cin>>n;
  32.     for(int i=1;i<=n;i++){ cin>>a[i]; pa[a[i]]=i; }
  33.     for(int i=1;i<=n;i++){ cin>>b[i]; pb[b[i]]=i; }
  34.     backtrack(1);
  35.     cout<<res;
  36.     return 0;
  37. }
  38. /*
  39.     Solve by: Truong Tuan Kiet - Informatics K36. Solve in 11h00 - 27/6/2025
  40. */
  41.  
  42.  
  43.  
  44.  
  45.  
  46.  
Success #stdin #stdout 0.01s 5272KB
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stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/ErnLf0
language:
C++14 (gcc 8.3)
created:
6 hours ago
visibility:
public

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