What Is the Binary Search in Data Structure?


Heather Bennett

A binary search is a fundamental algorithm in computer science and data structures. It is used to efficiently search for an element in a sorted array or list. The binary search algorithm follows a divide and conquer approach, which makes it much faster than linear search for large datasets.

How Does Binary Search Work?

The binary search algorithm works by repeatedly dividing the search space in half until the desired element is found or the remaining search space becomes empty.

To perform a binary search, the array or list must be sorted in ascending order. The algorithm starts by comparing the Target element with the middle element of the array. If they match, the search is successful, and the index of the element is returned.

If the Target element is smaller than the middle element, the algorithm continues searching only in the left half of the array. Otherwise, if the Target element is larger, it searches only in the right half.

This process is repeated recursively until either a match is found or there are no more elements left to search. If no match is found, -1 or an appropriate indicator can be returned to indicate that the Target element does not exist in the array.

Binary Search Algorithm

  1. Let low be 0 and high be n-1, where n is the size of the array.
  2. Repeat until low becomes greater than high:
    • Set mid as (low + high) / 2.
    • If arr[mid] equals Target:
      • The Target has been found at index mid.
      • Return mid and exit.
    • Else if arr[mid] is greater than Target:
      • Continue the search in the left half.
      • Set high as mid – 1.
    • Else:
      • Continue the search in the right half.
      • Set low as mid + 1.
  3. The Target element does not exist in the array. Return -1 or an appropriate indicator.

Time Complexity of Binary Search

The time complexity of binary search is O(log n), where n is the size of the array. This logarithmic time complexity makes binary search extremely efficient, especially for large datasets. By repeatedly halving the search space, binary search quickly converges to the desired element, reducing the number of comparisons required compared to linear search algorithms that have a time complexity of O(n).


The binary search algorithm is a powerful tool for searching for elements in sorted arrays or lists. Its efficiency and simplicity make it a popular choice in various applications, including database systems and information retrieval systems. By understanding how binary search works and its time complexity, programmers can optimize their code and improve performance when dealing with large datasets.

If you need to implement a search functionality in your program or application, consider using binary search for faster and more efficient results!

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