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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define int long long
  5.  
  6. const long double PI = 3.14159265359;
  7.  
  8. void solve()
  9. {
  10.     int n;
  11.     cin >> n;
  12.     vector<int> arr(n + 1);
  13.     for (int i = 1; i <= n; i++)
  14.         cin >> arr[i];
  15.  
  16.     int sum = 0;
  17.  
  18.     int parity[] = {n / 2, (n + 1) / 2};
  19.     // magn, sign, even - odd position
  20.     vector<array<int, 3>> vals;
  21.     for (int i = 1; i <= n; i++)
  22.     {
  23.         vals.push_back({abs(arr[i]), arr[i] < 0, i % 2});
  24.     }
  25.  
  26.     sort(vals.rbegin(), vals.rend());
  27.  
  28.     for (int i = 0; i < vals.size(); i++)
  29.     {
  30.         if (vals[i][1] == 0)
  31.         {
  32.             // pos
  33.             if (parity[vals[i][2]])
  34.                 sum += vals[i][0], parity[vals[i][2]]--;
  35.             else
  36.                 sum -= vals[i][0], parity[!vals[i][2]]--;
  37.         }
  38.         else
  39.         {
  40.             // neg
  41.             if (parity[!vals[i][2]])
  42.                 sum += vals[i][0], parity[!vals[i][2]]--;
  43.             else
  44.                 sum -= vals[i][0], parity[vals[i][2]]--;
  45.         }
  46.     }
  47.     cout << sum << '\n';
  48. }
  49.  
  50. signed main(void)
  51. {
  52.     ios_base::sync_with_stdio(0);
  53.     cin.tie(0);
  54.     cout.tie(0);
  55.     if (fopen("input.txt", "r"))
  56.     {
  57.         freopen("input.txt", "r", stdin);
  58.         freopen("output.txt", "w", stdout);
  59.     }
  60.     int t = 1;
  61.     cin >> t;
  62.     while (t--)
  63.     {
  64.         solve();
  65.     }
  66.     return 0;
  67. }
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin
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4
1
-3
4
1 -2 -3 4
5
-10 1 0 1 -10
2
6 -7
stdout
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-3
10
18
1
https://ideone.com/CeE2lx
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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