Tipify binary-search

content/snippets/js/s/binary-search.md

@@ -1,39 +1,46 @@
 ---
-title: Binary search
-type: snippet
+title: Binary search in a sorted JavaScript array
+shortTitle: Binary search
+type: tip
 language: javascript
 tags: [algorithm,array]
 cover: zen-indoors
-excerpt: Finds the index of a given element in a sorted array using the binary search algorithm.
+excerpt: Use the binary search algorithm to find the index of a given element in a sorted array.
 listed: true
-dateModified: 2020-12-29
+dateModified: 2024-07-20
 ---
 
-Finds the index of a given element in a sorted array using the binary search algorithm.
+The [binary search algorithm](https://en.wikipedia.org/wiki/Binary_search) is a fast and efficient way to **find the index of a given element in a sorted array**. It works by repeatedly dividing the search interval in half, narrowing down the possible locations of the element.
 
-- Declare the left and right search boundaries, `l` and `r`, initialized to `0` and the `length` of the array respectively.
-- Use a `while` loop to repeatedly narrow down the search subarray, using `Math.floor()` to cut it in half.
-- Return the index of the element if found, otherwise return `-1`.
+A binary search is much faster than a [linear search](/js/s/linear-search), especially for large arrays, as it has a **time complexity** of `O(log n)`. However, it requires the array to be sorted beforehand.
 
-> [!NOTE]
->
-> Does not account for duplicate values in the array.
+In order to implement the algorithm, we need to keep track of the left and right **boundaries** of the search interval, and repeatedly divide it in half until the element is found or the interval is empty. The boundaries are initialized to `0` and the length of the array, respectively.
+
+Then, using a `while` **loop**, we calculate the **middle index** of the current interval and compare the element at that index with the target element. If the element is **found**, we return the index. Otherwise, we update the boundaries based on the comparison and continue the search.
+
+If the element is **not found** after the loop, we return `-1` to indicate that the element is not present in the array.
 
 ```js
 const binarySearch = (arr, item) => {
-  let l = 0,
-    r = arr.length - 1;
+  let l = 0, r = arr.length - 1;
+
   while (l <= r) {
     const mid = Math.floor((l + r) / 2);
     const guess = arr[mid];
+
     if (guess === item) return mid;
     if (guess > item) r = mid - 1;
     else l = mid + 1;
   }
+
   return -1;
 };
 
 binarySearch([1, 2, 3, 4, 5], 1); // 0
 binarySearch([1, 2, 3, 4, 5], 5); // 4
 binarySearch([1, 2, 3, 4, 5], 6); // -1
 ```
+
+> [!NOTE]
+>
+> This implementation **does not account for duplicate values** in the array.