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  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. int A(int n) {
  6.     if (n == 1)
  7.         return 0;
  8.  
  9.     // k == 3^m
  10.     int k = 1;
  11.     while (3*k < n) k *= 3;
  12.  
  13.     return A((n - 1) % k + 1) + ((n <= 2*k) ? k : 2*k);
  14. }
  15.  
  16. int
  17. main()
  18. {
  19.     for (auto n: {1, 2, 3, 4, 5, 6, 9, 123457, 1000000000})
  20.         cout << n << " " << A(n) << endl;
  21. }
  22.  
Success #stdin #stdout 0.01s 5300KB
comments (?)
stdin 
Standard input is empty
stdout 
1 0
2 1
3 2
4 3
5 4
6 5
9 8
123457 123456
1000000000 999999999
https://ideone.com/bk903A
language:
C++14 (gcc 8.3)
created:
179 days ago
visibility:
secret

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