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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. // GCD and LCM
  5. int gcd(int a, int b) {
  6.     return b == 0 ? a : gcd(b, a % b);
  7. }
  8. int lcm(int a, int b) {
  9.     return (a / gcd(a, b)) * b;
  10. }
  11.  
  12. // Checks if it's possible to satisfy A and B with N numbers
  13. bool isEnough(int N, int Num1, int Num2, int X, int Y) {
  14.     int L = lcm(X, Y);
  15.  
  16.     int onlyX = N / X - N / L;  // divisible by X only (usable for B)
  17.     int onlyY = N / Y - N / L;  // divisible by Y only (usable for A)
  18.     int neither = N - (N / X + N / Y - N / L); // not divisible by X or Y
  19.  
  20.     int needA = max(0, Num1 - onlyY);  // A needs more from neither
  21.     int needB = max(0, Num2 - onlyX);  // B needs more from neither
  22.  
  23.     return (needA + needB) <= neither;
  24. }
  25.  
  26. // Binary search to find the minimum N
  27. int happyPeople(int Num1, int Num2, int X, int Y) {
  28.     int low = 1, high = 2000000000, ans = -1;
  29.  
  30.     while (low <= high) {
  31.         int mid = low + (high - low) / 2;
  32.  
  33.         if (isEnough(mid, Num1, Num2, X, Y)) {
  34.             ans = mid;
  35.             high = mid - 1; // Try smaller N
  36.         } else {
  37.             low = mid + 1;
  38.         }
  39.     }
  40.  
  41.     return ans;
  42. }
  43.  
  44. int main() {
  45.     int Num1, Num2, X, Y;
  46.     cin >> Num1 >> Num2 >> X >> Y;
  47.     cout << happyPeople(Num1, Num2, X, Y) << endl;
  48.     return 0;
  49. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin 
10 5 7 11
stdout 
15
https://ideone.com/JMnkiU
language:
C++14 (clang 8.0)
created:
5 days ago
visibility:
public

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