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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_all = 0;
  20.     for(int i = 0; i < n; i++) {
  21.         cin >> a[i].ff;
  22.         a[i].ss = i + 1; // Store 1-based index
  23.         sum_all += a[i].ff;
  24.     }
  25.  
  26.     sort(all(a));
  27.  
  28.     // Case 1: Target is 0 survivors
  29.     if (m == 0) {
  30.         // The strongest elf (a[n-1]) must take damage >= their health.
  31.         // Damage comes from all other n-1 elves attacking them.
  32.         int damage_avail = sum_all - a[n-1].ff;
  33.  
  34.         if (damage_avail >= a[n-1].ff) {
  35.             cout << n - 1 << endl;
  36.             // Everyone attacks the King
  37.             for(int i = 0; i < n - 1; i++) {
  38.                 cout << a[i].ss << " " << a[n-1].ss << endl;
  39.             }
  40.         } else {
  41.             cout << -1 << endl;
  42.         }
  43.         return;
  44.     }
  45.  
  46.  
  47.     if (n == m) {
  48.         cout << 0 << endl;
  49.         return;
  50.     }
  51.  
  52.     vector<pair<int, int>> moves;
  53.  
  54.     for (int i = 0; i < n - m - 1; i++) {
  55.         moves.pb({a[i].ss, a[i+1].ss});
  56.     }
  57.  
  58.     moves.pb({a[n-m-1].ss, a[n-1].ss});
  59.  
  60.     cout << sz(moves) << endl;
  61.     for(auto p : moves) {
  62.         cout << p.ff << " " << p.ss << endl;
  63.     }
  64. }
  65.  
  66. int32_t main() {
  67.     fast_io;
  68.     int t;
  69.     cin >> t;
  70.     while(t--) {
  71.         solve();
  72.     }
  73.     return 0;
  74. }
Success #stdin #stdout 0.01s 5280KB
comments (?)
stdin
copy 
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
copy 
2
1 3
3 2
0
2
1 3
2 3
2
1 2
2 3
1
1 3
3
1 2
2 3
3 4
5
3 2
4 2
6 2
1 2
5 2
https://ideone.com/0dspY3
language:
C++ (gcc 8.3)
created:
6 days ago
visibility:
public

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