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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main(){
  5.     ios::sync_with_stdio(false);
  6.     cin.tie(nullptr);
  7.     int N;
  8.     cin >> N;
  9.     vector<int> P(N+1), pos(N+1);
  10.     for(int i=1;i<=N;i++){cin>>P[i];pos[P[i]]=i;}
  11.     vector<pair<int,int>> ops;
  12.     for(int i=1;i<=N;i++){
  13.         int p=pos[i];
  14.         if(p==i) continue;
  15.         int L=p-i+1;
  16.         if(L%2){ // 홀수 길이 → 바로 뒤집기
  17.             ops.emplace_back(i,p);
  18.             reverse(P.begin()+i,P.begin()+p+1);
  19.             for(int k=i;k<=p;k++) pos[P[k]]=k;
  20.         }else{ // 짝수 길이 → 두 번 홀수로 해결
  21.             ops.emplace_back(i,p+1);
  22.             reverse(P.begin()+i,P.begin()+p+2);
  23.             for(int k=i;k<=p+1;k++) pos[P[k]]=k;
  24.             p=pos[i];
  25.             ops.emplace_back(i+1,p);
  26.             reverse(P.begin()+i+1,P.begin()+p+1);
  27.             for(int k=i+1;k<=p;k++) pos[P[k]]=k;
  28.         }
  29.     }
  30.     cout<<ops.size()<<"\n";
  31.     for(auto &op:ops) cout<<op.first<<" "<<op.second<<"\n";
  32. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
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6
6 5 4 3 2 1
stdout
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12
1 7
2 2
2 4
3 3
3 3
4 2
4 6
5 5
5 5
6 4
6 8
7 7
https://ideone.com/VVFhcY
language:
C++ (gcc 8.3)
created:
17 days ago
visibility:
public

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