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  1. #include <bits/stdc++.h>
  2. #define ll long long
  3.  
  4. using namespace std;
  5.  
  6. const int MOD = 1e9 + 7;
  7.  
  8. void solve(){
  9. 	int n;
  10. 	cin >> n;
  11. 	vector<int> b(n / 2);
  12. 	vector<int> c(n + 1);
  13. 	bool done = false;
  14. 	for(int i = 0; i < n / 2; i++){
  15. 		int x;
  16. 		cin >> x;
  17. 		c[x]++;
  18. 		if(c[x] > 1){
  19. 			done = true;
  20. 		}
  21. 		b[i] = x;
  22. 	}
  23. 	if(done){
  24. 		cout << -1 << "\n";
  25. 		return;
  26. 	}
  27. 	vector<int> d;
  28. 	for(int i = 1; i <= n; i++)if(!c[i])d.push_back(i);
  29.  
  30.  
  31. 	vector<int> ans(n);
  32. 	set<int> allow;
  33. 	int idx = 0;
  34. 	for(int i = 0; i < n; i += 2){
  35. 		ans[i + 1] = b[idx];
  36. 		if(d[idx] < b[idx]){
  37. 			allow.insert(d[idx]);
  38. 			idx++;
  39. 		}else{
  40. 			if(allow.size() == 0 || *(allow.begin()) > b[idx]){
  41.  
  42. 				cout << -1 << "\n";
  43. 				return;
  44. 			}
  45. 			auto y = allow.lower_bound(b[idx]);
  46. 			y--;
  47. 			ans[i] = *y;
  48. 			allow.erase(y);
  49. 			allow.insert(d[idx]);
  50. 			idx++;
  51. 		}
  52. 	}
  53. 	for(int i = 0; i < n; i += 2){
  54. 		if(ans[i] == 0){
  55. 			ans[i] = *(allow.begin());
  56. 			allow.erase(ans[i]);
  57. 		}
  58. 	}
  59. 	for(auto x: ans)cout << x<< " ";
  60. 	cout << "\n";
  61.  
  62. }
  63.  
  64. int main(){
  65. 	ios_base::sync_with_stdio(false);
  66. 	cin.tie(nullptr);
  67.  
  68. 	int t = 1;
  69. 	cin >> t;
  70.  
  71. 	for(int i = 1; i <= t; i++){
  72. 		solve();
  73. 	}
  74. 	return 0;
  75. }
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
copy 
6
6
4 3 6
4
2 4
8
8 7 2 3
6
6 4 2
4
4 4
8
8 7 4 5
stdout
copy 
1 4 2 3 5 6 
1 2 3 4 
-1
3 6 5 4 1 2 
-1
1 8 2 7 6 4 3 5
https://ideone.com/okvwRJ
language:
C++14 (gcc 8.3)
created:
11 days ago
visibility:
public

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