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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. // Speed
  5. #define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
  6. // Typedefs
  7. #define int long long
  8. #define pb push_back
  9. #define ff first
  10. #define ss second
  11. #define all(x) (x).begin(), (x).end()
  12. #define sz(x) ((int)(x).size())
  13. #define endl '\n'
  14.  
  15. void solve() {
  16.     int n, m;
  17.     cin >> n >> m;
  18.     vector<pair<int, int>> a(n);
  19.     int sum_others = 0;
  20.  
  21.     for(int i = 0; i < n; i++) {
  22.         cin >> a[i].ff;
  23.         a[i].ss = i + 1; 
  24.     }
  25.  
  26.     sort(all(a));
  27.  
  28.     if (m == 0) {
  29.         int current_king_hp = a[n-1].ff;
  30.         for(int i = 0; i < n - 1; i++) sum_others += a[i].ff;
  31.  
  32.         if (sum_others < current_king_hp) {
  33.             cout << -1 << endl;
  34.             return;
  35.         }
  36.  
  37.         vector<pair<int, int>> moves;
  38.         for(int i = 0; i < n - 1; i++) {
  39.             if (i == n - 2) {
  40.                 moves.pb({a[i].ss, a[n-1].ss});
  41.             }
  42.             else if (current_king_hp > a[i].ff) {
  43.                 moves.pb({a[i].ss, a[n-1].ss});
  44.                 current_king_hp -= a[i].ff;
  45.             }
  46.             else {
  47.                 moves.pb({a[i].ss, a[i+1].ss});
  48.             }
  49.         }
  50.  
  51.         cout << sz(moves) << endl;
  52.         for(auto p : moves) cout << p.ff << " " << p.ss << endl;
  53.         return;
  54.     }
  55.  
  56.  
  57.     if (n < 2 * m) {
  58.         cout << -1 << endl;
  59.         return;
  60.     }
  61.  
  62.  
  63.     vector<pair<int, int>> moves;
  64.  
  65.     int trash_count = n - 2 * m;
  66.     int first_target_idx = n - 2 * m;
  67.  
  68.     if (trash_count > 0) {
  69.         for (int i = 0; i < trash_count; i++) {
  70.             if (i == trash_count - 1) {
  71.                 moves.pb({a[i].ss, a[first_target_idx].ss});
  72.             } else {
  73.                 moves.pb({a[i].ss, a[i+1].ss});
  74.             }
  75.         }
  76.     }
  77.  
  78.     for (int i = 0; i < m; i++) {
  79.         int target_idx = n - 2 * m + i;
  80.         int survivor_idx = n - m + i;
  81.  
  82.         moves.pb({a[survivor_idx].ss, a[target_idx].ss});
  83.     }
  84.  
  85.     cout << sz(moves) << endl;
  86.     for(auto p : moves) {
  87.         cout << p.ff << " " << p.ss << endl;
  88.     }
  89. }
  90.  
  91. int32_t main() {
  92.     fast_io;
  93.     int t;
  94.     cin >> t;
  95.     while(t--) {
  96.         solve();
  97.     }
  98.     return 0;
  99. }
Success #stdin #stdout 0s 5308KB
comments (?)
stdin 
7
4 2
1 4 2 3
2 2
6 7
3 0
1 2 3
3 1
1 2 3
3 2
1 2 3
4 1
2 3 4 5
6 0
998244353 1000000000 314159265 676767677 999999999 987654321
stdout 
2
4 1
2 3
-1
2
1 3
2 3
2
1 2
3 2
-1
3
1 2
2 3
4 3
5
3 2
4 2
6 1
1 5
5 2
https://ideone.com/IWaOcq
language:
C++ (gcc 8.3)
created:
13 days ago
visibility:
public

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