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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.  
  8.     int n;
  9.     cin >> n;
  10.     vector<int> P(n);
  11.     for (int i = 0; i < n; i++) cin >> P[i];
  12.  
  13.     // 역전 개수의 parity 구하기
  14.     long long inv = 0;
  15.     for (int i = 0; i < n; i++) {
  16.         for (int j = i+1; j < n; j++) {
  17.             if (P[i] > P[j]) inv++;
  18.         }
  19.     }
  20.  
  21.     long long total = 1LL * n * (n-1) / 2;
  22.  
  23.     if ((inv % 2) != (total % 2)) {
  24.         cout << 0 << "\n";
  25.         return 0;
  26.     }
  27.  
  28.     cout << 1 << "\n";
  29.     // 교환 순서 아무거나: 예를 들어 (i,j) with i<j 사전순 출력
  30.     for (int j = 2; j <= n; j++) {
  31.         for (int i = 1; i < j; i++) {
  32.             cout << i << " " << j << "\n";
  33.         }
  34.     }
  35.  
  36.     return 0;
  37. }
Success #stdin #stdout 0.01s 5272KB
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https://ideone.com/vXgDpI
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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