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  1. /*
  2. ==> Don't stop when you're tired, stop when you're done.
  3. ==> From the river to the sea, Palestine will be free.
  4. --> @author: MIDORIYA_
  5. */
  6. //*==============================================================
  7. #include <bits/stdc++.h>
  8. using namespace std;
  9. typedef long long ll;
  10. typedef double db;
  11. typedef long double ld;
  12. typedef pair<int, int> pii;
  13. typedef pair<ll, ll> pll;
  14. typedef vector<int> vi;
  15. typedef vector<ll> vll;
  16. typedef vector<db> vd;
  17. typedef vector<ld> vld;
  18. typedef vector<bool> vb;
  19. typedef vector<vector<ll>> vvl;
  20. typedef vector<vector<int>> vvi;
  21. typedef vector<pii> vii;
  22. typedef set<int> si;
  23. typedef set<ll> sl;
  24. #define pb push_back
  25. #define pf push_front
  26. #define popb pop_back
  27. #define popf pop_front
  28. #define fi first
  29. #define se second
  30. #define all(x) x.begin(), x.end()
  31. #define rall(x) x.rbegin(), x.rend()
  32. #define endl "\n"
  33. const int MOD = 998244353, mod = 1e9 + 7, maxA = 1e5 + 5;
  34. #define time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs";
  35. //*===================>>>FastIO - FileIO<<<=========
  36. void fastIO()
  37. {
  38.     ios_base::sync_with_stdio(false);
  39.     cin.tie(nullptr);
  40.     cout.tie(nullptr);
  41. }
  42. void fileIO()
  43. {
  44. #ifndef ONLINE_JUDGE
  45.     freopen("in.txt", "r", stdin);
  46.     freopen("out.txt", "w", stdout);
  47. #endif
  48. }
  49. //*===================>>>ONE-FOR-ALL<<<=============
  50. void OneForAll()
  51. {
  52.     ll a, b;
  53.     cin >> a >> b;
  54.  
  55.     ll maxEvenSum = -1;
  56.     if (b & 1)
  57.     {
  58.         if (a & 1)
  59.         {
  60.             cout << a * b + 1 << endl;
  61.         }
  62.         else
  63.         {
  64.             cout << "-1" << endl;
  65.         }
  66.         return;
  67.     }
  68.  
  69.     vector<ll> vec;
  70.  
  71.     vec.pb(1);
  72.     if (b > 1)
  73.         vec.pb(b);
  74.  
  75.     if (b % 2 == 0)
  76.     {
  77.         vec.pb(2);
  78.         vec.pb(b / 2);
  79.     }
  80.  
  81.     for (ll k = 1; k * k <= b && k <= 1000; k++)
  82.     {
  83.         if (b % k == 0)
  84.         {
  85.             vec.pb(k);
  86.             if (k != b / k)
  87.             {
  88.                 vec.pb(b / k);
  89.             }
  90.         }
  91.     }
  92.     sort(all(vec));
  93.     vec.erase(unique(all(vec)), vec.end());
  94.  
  95.     for (ll k : vec)
  96.     {
  97.         ll sum = a * k + b / k;
  98.         if (sum % 2 == 0)
  99.         {
  100.             maxEvenSum = max(maxEvenSum, sum);
  101.         }
  102.     }
  103.  
  104.     cout << maxEvenSum << endl;
  105. }
  106.  
  107. int main()
  108. {
  109.     fastIO();
  110.     // fileIO();
  111.  
  112.     ll tc = 1, t = 1;
  113.     cin >> t;
  114.     while (t--)
  115.     {
  116.         // cout << "Case " << tc++ << ": ";
  117.         OneForAll();
  118.     }
  119.     time;
  120.     return 0;
  121. }
Success #stdin #stdout #stderr 0.01s 5324KB
comments (?)
stdin
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Standard input is empty
stdout
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23328962683090
stderr
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Time Taken: 0.006038 Secs
https://ideone.com/tZeZPy
language:
C++14 (gcc 8.3)
created:
9 hours ago
visibility:
public

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