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  1. // Marvyn Jesse De La Torre            CS1A     Chapter 8 #3 pg.487
  2. //
  3. /*************************************************************
  4. *
  5. * Binary Search Lottery
  6. *
  7. * This program uses binary search to find a number in
  8. * a sorted array of lottery numbers.
  9. *
  10. * Input:
  11. *   win: The number entered by the user
  12. *
  13. * Output:
  14. *   Displays whether the number was found.
  15. *************************************************************/
  16.  
  17. #include <iostream>
  18. using namespace std;
  19.  
  20. int binary(int arr[], int size, int win);
  21.  
  22. int main()
  23. {
  24.     int arr[] = {
  25.         13579, 26791, 26792, 33445, 55555,
  26.         62483, 77777, 79422, 85647, 93121
  27.     };
  28.  
  29.     int size = sizeof(arr) / sizeof(arr[0]);
  30.     int win;
  31.  
  32.     cout << "Enter the number to search for: ";
  33.     cin >> win;
  34.  
  35.     int position = binary(arr, size, win);
  36.  
  37.     if (position == -1)
  38.     {
  39.         cout << "Number not found." << endl;
  40.     }
  41.     else
  42.     {
  43.         cout << "Number found." << endl;
  44.     }
  45.  
  46.     return 0;
  47. }
  48.  
  49. int binary(int arr[], int size, int win)
  50. {
  51.     int first = 0;
  52.     int last = size - 1;
  53.     int position = -1;
  54.  
  55.     while (position == -1 && first <= last)
  56.     {
  57.         int middle = (first + last) / 2;
  58.  
  59.         if (arr[middle] == win)
  60.         {
  61.             position = middle;
  62.         }
  63.         else if (arr[middle] > win)
  64.         {
  65.             last = middle - 1;
  66.         }
  67.         else
  68.         {
  69.             first = middle + 1;
  70.         }
  71.     }
  72.  
  73.     return position;
  74. }
Success #stdin #stdout 0s 5352KB
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Enter the number to search for: Number found.
https://ideone.com/HhdO4H
language:
C++ (gcc 8.3)
created:
21 hours ago
visibility:
public

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