Recursive Approach
- BASE CONDITION: If the starting index is greater than the ending index return false.
- Compute the middle index.
- Compare the middle element with the number x. If equal return true.
- If greater, call the same function with ending index = middle-1 and repeat step 1.
- If smaller, call the same function with starting index = middle+1 and repeat step 1.
Example: This example shows the use of the above-explained approach.
javascript
let recursiveFunction = function (arr, x, start, end) { // Base Condition if (start > end) return false; // Find the middle index let mid = Math.floor((start + end) / 2); // Compare mid with given key x if (arr[mid] === x) return true; // If element at mid is greater than x, // search in the left half of mid if (arr[mid] > x) return recursiveFunction(arr, x, start, mid - 1); else // If element at mid is smaller than x, // search in the right half of mid return recursiveFunction(arr, x, mid + 1, end);}// Driver codelet arr = [1, 3, 5, 7, 8, 9];let x = 5;if (recursiveFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!");}else { console.log("Element not found!"); }x = 6;if (recursiveFunction(arr, x, 0, arr.length - 1)) { console.log("Element found!");}else { console.log("Element not found!"); } |
Output
Element found! Element not found!
Time Complexity: O(logN)
Auxiliary Space: O(1)
Binary Search In JavaScript
Binary Search is a searching technique that works on the Divide and Conquer approach. It is used to search for any element in a sorted array. Compared with linear, binary search is much faster with a Time Complexity of O(logN), whereas linear search works in O(N) time complexity
Examples:
Input : arr[] = {1, 3, 5, 7, 8, 9}, x = 5
Output : Element found!
Input : arr[] = {1, 3, 5, 7, 8, 9}, x = 6
Output : Element not found!
Note: Assuming the array is sorted.
These are the following ways to do Binary Search in JavaScript:
Table of Content
- Recursive Approach
- Iterative Approach
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