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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int long long 
  4. vector<int> vec;
  5. int n;
  6.  
  7. int recur(int l, int r) {
  8.     int ans = 0;
  9.     if (l + 1 >= r) {
  10.         return ans;
  11.     }
  12.     int mid = (l + r) / 2;
  13.     ans += recur(l, mid);
  14.     ans += recur(mid, r);
  15.  
  16.     // Debugging output
  17.     // cout << l << " " << r << endl;
  18.  
  19.     // Count inversions
  20.     for(int i = l; i < r; i++){
  21.     	cout << vec[i] << " ";
  22.     }cout << endl; 
  23.     int i = l, j = mid;
  24.     int k = 0;
  25.     int ans1 = 0; 
  26.     while (j < r) {
  27.         if(i + 1 == mid || vec[j] > vec[i]){
  28.             // while(vec[k] < vec[j]){
  29.             //     ans1 -= vec[k];
  30.             //     k++;
  31.             // }
  32.             ans += vec[j] * (i - k) + ans1;
  33.             // cout << ans << " " << k << endl; 
  34.             // cout << ans << " " << vec[j] << " " << ans1 << endl; 
  35.             j++;
  36.         	continue;
  37.         }
  38.         if (vec[i] > vec[j]) {
  39.             i++;
  40.             ans1 += vec[i];
  41.             // cout << vec[i] << " ";
  42.  
  43.         } 
  44.     }
  45.     cout << endl; 
  46.  
  47.  
  48.     inplace_merge(vec.begin() + l, vec.begin() + mid, vec.begin() + r);
  49.     return ans;
  50. }
  51.  
  52. signed main() {
  53.     cin >> n;
  54.     vec.resize(n);
  55.     for (int i = 0; i < n; i++) {
  56.         cin >> vec[i];
  57.     }
  58.     cout << recur(0, n) << endl;
  59. }
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin
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5
5 4 2 1 3
stdout
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5 4 

1 3 

2 1 3 

4 5 1 2 3 

38
https://ideone.com/e4Z8b8
language:
C++14 (gcc 8.3)
created:
5 days ago
visibility:
public

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