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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int              long long int
  4. #define double           long double
  5. inline int power(int a, int b) {
  6.     int x = 1;
  7.     while (b) {
  8.         if (b & 1) x *= a;
  9.         a *= a;
  10.         b >>= 1;
  11.     }
  12.     return x;
  13. }
  14.  
  15.  
  16. const int M = 1000000007;
  17. const int N = 3e5+9;
  18. const int INF = 2e9+1;
  19. const int LINF = 2000000000000000001;
  20.  
  21. //_ ***************************** START Below *******************************
  22.  
  23.  
  24. void consistency(int n) {
  25.  
  26.     int totalSum = n*(n+1)/2;
  27.     if(totalSum & 1){
  28.     	cout << -1 << endl;
  29.     	return;
  30.     }
  31.  
  32.     int halfSum = totalSum/2;
  33.  
  34.     vector<int> subset;
  35.     int sum = 0;
  36.     int i=1;
  37.     while(sum + i <= halfSum){
  38.     	sum += i;
  39.     	subset.push_back(i);
  40.     	i++;
  41.     }
  42.  
  43.     int last = subset.back();
  44.     subset.pop_back();
  45.     sum -= last;
  46.  
  47.     subset.push_back(n);
  48.     sum += n;
  49.  
  50.     vector<int> a, b;
  51.  
  52.     b.push_back(last);
  53.     while(i<n){
  54.     	b.push_back(i);
  55.     	i++;
  56.     }
  57.  
  58.     int remove = sum - halfSum;
  59.     for(int i=0; i<subset.size(); i++){
  60.     	if(subset[i] == remove ){
  61.     		b.push_back(subset[i]);
  62.     	}
  63.     	else {
  64.     		a.push_back(subset[i]);
  65.     	}
  66.     }
  67.  
  68.     sort(begin(b), end(b));
  69.  
  70.     vector<int> p;
  71.     for(int i=0; i<a.size(); i++){
  72.     	cout << a[i] << " ";
  73.     }
  74.     cout << " |  ";
  75.     for(int i=0; i<b.size(); i++){
  76.     	cout << b[i] << " ";
  77.     }
  78.     cout << endl;
  79.  
  80. }
  81.  
  82.  
  83. void solve() {
  84.  
  85.     int n;
  86.     cin >> n ;
  87.  
  88.     consistency(n);
  89.  
  90. }
  91.  
  92.  
  93.  
  94.  
  95.  
  96. int32_t main() {
  97.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  98.  
  99.     int t = 1;
  100.     cin >> t;
  101.     while (t--) {
  102.         solve();
  103.     }
  104.  
  105.     return 0;
  106. }
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
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4
8
11
6
12
stdout
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1 2 3 4 8  |  5 6 7 
1 2 3 4 5 6 11  |  7 8 9 10 
-1
2 3 4 5 6 7 12  |  1 8 9 10 11
https://ideone.com/tpQfru
language:
C++14 (gcc 8.3)
created:
9 hours ago
visibility:
public

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