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  1. #include <iostream>
  2.  
  3. using std::cin;
  4. using std::cout;
  5. using std::endl;
  6.  
  7. int main() {
  8.     constexpr char yes = 'y';
  9.     constexpr char no = 'n';
  10.  
  11.     int left = 1;
  12.     int right = 100;
  13.  
  14.     cout << "Guess the number from " << left << " to " << right << "." << endl;
  15.     cout << "Further enter \"" << yes << "\" if the answer is yes, or \"" << no << "\" if the answer is no." << endl;
  16.  
  17.     while (right - left > 1) {
  18.         int approximation = (left + right) / 2;
  19.         cout << "Is your number less than " << approximation << "?" << endl;
  20.  
  21.         char answer = ' ';
  22.         while (true) {
  23.             cout << ">>> ";
  24.             cin >> answer;
  25.             if (answer == yes || answer == no) {
  26.                 break;
  27.             } else {
  28.                 cout << "I do not get it. Please, follow the above rule entering the answer." << endl;
  29.             }
  30.         }
  31.  
  32.         switch (answer)	{
  33.         case yes:
  34.             right = approximation;
  35.             break;
  36.         case no:
  37.             left = approximation;
  38.             break;
  39.         default:
  40.             break;
  41.         }
  42.     }
  43.  
  44.     cout << "Your number is " << left << "." << endl;
  45. }
  46.  
Success #stdin #stdout 0s 5676KB
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stdin
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y
n
n
n
y
y
stdout
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Guess the number from 1 to 100.
Further enter "y" if the answer is yes, or "n" if the answer is no.
Is your number less than 50?
>>> Is your number less than 25?
>>> Is your number less than 37?
>>> Is your number less than 43?
>>> Is your number less than 46?
>>> Is your number less than 44?
>>> Your number is 43.
https://ideone.com/IUcG2T
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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