Binary Search

  1. 'use strict';
  3. /* Binary search number algorithm */
  5. let i = 0;
  7. const binarySearch = ({ array, head = 0, number, tail }) => {
  9.     if (i > 10) return 'stack overflow'; i += 1;
  11.     tail = tail || array.length;
  13.     const remainingArray = array.slice(head, tail);
  15.     const index = Math.floor(remainingArray.length / 2);
  17.     const normalizedIndex = head + index;
  19.     if (remainingArray[index] === number) {
  20.         console.log('found in index ', normalizedIndex);
  22.         return normalizedIndex;
  23.     }
  25.     if (number < remainingArray[index]) {
  26.         tail = normalizedIndex;
  27.     } else {
  28.         head = normalizedIndex;
  29.     }
  31.     console.log('head', head, 'tail', tail, remainingArray, 'index', normalizedIndex);
  33.     return binarySearch({ array, head, number, tail });
  34. };
  1. // Tests
  2. let array;
  4. array = [0,10,20,30,40,50,60,70,80,90,100,110,120,130,140,150];
  5. console.log(binarySearch({ array, number: 20 }) );
  6. i = 0;
  8. console.log(binarySearch({ array, number: 70 }) );
  9. i = 0;
  11. console.log(binarySearch({ array, number: 130 }) );
  12. i = 0;
  14. console.log(binarySearch({ array, number: 0 }) );
  15. i = 0;
  17. array = [0,1,2,3,4,5];
  18. console.log(binarySearch({ array, number: 5 }) );
  20. array = [0,1,2,3,4,5,6];
  21. console.log(binarySearch({ array, number: 4 }) );