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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int getHighestTwoPowerFactor(int from);
  5. int getNearestTwoPower(int from);
  6.  
  7. int getTrains(int from, int to) {
  8.     cout << from << " ";
  9.     int count = 1;
  10.  
  11.     if(from == 0) {
  12.         from = getNearestTwoPower(to);
  13.         count++;
  14.         cout << from << " ";
  15.     } else if(from % 2 != 0) {
  16.         from++;
  17.         count++;
  18.         cout << from << " ";
  19.     }
  20.  
  21.     if(from == to)
  22.         return count;
  23.  
  24.     int getHighestTwoPowerFactor = 1;
  25.  
  26.     while(true) {
  27.         getHighestTwoPowerFactor = ::getHighestTwoPowerFactor(from);
  28.         from += getHighestTwoPowerFactor;
  29.         count++;
  30.         if(from > to) {
  31.             from -= getHighestTwoPowerFactor;
  32.             count--;
  33.             break;
  34.         } else if(from == to) {
  35.             cout << from << " ";
  36.             return count;
  37.         }
  38.         cout << from << " ";
  39.     }
  40.  
  41.     while(from < to) {
  42.         while(from + getHighestTwoPowerFactor > to) {
  43.             getHighestTwoPowerFactor /= 2;
  44.         }
  45.         from += getHighestTwoPowerFactor;
  46.         count++;
  47.         cout << from << " ";
  48.     }
  49.     cout << endl;
  50.     return count;
  51. }
  52.  
  53. int getHighestTwoPowerFactor(int from) {
  54.     if((from & (from - 1)) == 0)
  55.         return from;
  56.  
  57.     int count = 0;
  58.     while(from % 2 == 0) {
  59.         from >>= 1;
  60.         count++;
  61.     }
  62.     return 1 << count;
  63. }
  64.  
  65. int getNearestTwoPower(int from) {
  66.     if((from & (from - 1)) == 0)
  67.         return from;
  68.  
  69.     int count = 0;
  70.     while(from != 0) {
  71.         from >>= 1;
  72.         count++;
  73.     }
  74.     return 1 << (count - 1);
  75. }
  76.  
  77. int main() {
  78.     int from = 3, to = 17;
  79.     int result = getTrains(from, to);
  80.     cout << "Total steps: " << result << endl;
  81.     return 0;
  82. }
Success #stdin #stdout 0.01s 5208KB
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stdin
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Standard input is empty
stdout
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3 4 8 16 17 
Total steps: 5
https://ideone.com/cxTmRd
language:
C++ (gcc 8.3)
created:
8 days ago
visibility:
public

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