Binary Search Algorithm: Function, Benefits, Time & Space Complexity

# Binary Search Algorithm: Function, Benefits, Time & Space Complexity

Last updated:
24th Jan, 2024
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## Introduction

In any computational system, the search is one of the most critical functionalities to develop. Search techniques are used in file retrievals, indexing, and many other applications. There are many search techniques available. One of which is the binary search technique.

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binary search algorithm works on the idea of neglecting half of the list on every iteration. It keeps on splitting the list until it finds the value it is looking for in a given list. A binary search algorithm is a quick upgrade to a simple linear search algorithm.

This article will discuss areas like the complexity of binary search algorithm is and binary search worse case along with giving a brief idea of binary search algorithm first, along with best and worse case complexity of binary search algorithm.

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## What is Binary Search Algorithm?

Binary search is a highly efficient search algorithm to locate a specific target value within a sorted array or list. It operates by repeatedly dividing the search interval in half, significantly reducing the number of comparisons required to find the target. The algorithm begins by examining the middle element of the array and comparing it to the target. If the middle element matches the target, the search concludes successfully. If the middle element is greater than the target, the search continues in the left half of the array; if it’s smaller, the search continues in the right half. This process iterates until the target is found or the search interval becomes empty.

Due to its halving nature, Binary search complexity exhibits an impressive time complexity of O(log n), where n represents the number of elements in the array. This makes binary search particularly effective for large datasets, offering a substantial improvement over linear search algorithms with a time complexity of O(n). However, binary search demands a precondition of sorted data, which might necessitate sorting the array initially. While incredibly efficient for sorted data, binary search is less suitable for small or frequently changing data due to the initial sorting overhead.

The history of the binary search algorithm dates back to ancient times when humans were developing manual methods to search for specific elements in a sorted list. While the formal algorithmic description we know today emerged in the field of computer science, the fundamental concept has roots in various historical practices.

### 1. Ancient Methods

The basic idea of binary search can be traced back to ancient methods of searching for elements in a sorted list. In ancient manuscripts or books, if someone was looking for a particular passage or information, they might start by opening the book in the middle. Based on whether the target passage was before or after the midpoint, they would then eliminate half of the remaining pages and repeat the process until they found the desired information.

### 2. John Mauchly’s Early Use (1946)

The concept of binary search was formalized in the field of electronic computing during the mid-20th century. John Mauchly used a binary search algorithm in 1946. The ENIAC, one of the earliest electronic general-purpose computers, was programmed to perform a binary search on sorted punched cards.

### 3. Algorithmic Description by Derrick Henry Lehmer (1948)

The algorithmic description of binary search as we recognize it today is credited to Derrick Henry Lehmer, an American mathematician and computer scientist. Lehmer published a paper in 1948 titled “Teaching an Electronic Computer to Play a Game,” where he described the binary search algorithm as part of a guessing game played on the SWAC (Standards Western Automatic Computer) computer.

### 4. Inclusion in Sorting and Searching Libraries

As computers evolved, binary search became a fundamental part of sorting and searching libraries. Its efficiency in quickly locating elements in a sorted dataset made it a staple in computer science and programming. Sorting and searching algorithms, including binary search, played a crucial role in the development of early programming languages and paved the way for more sophisticated algorithms.

### 5. Algorithmic Analysis and Refinement

Over the years, researchers and computer scientists have analyzed the time and space complexity of the binary search algorithm, leading to a better understanding of its performance characteristics. Algorithmic refinements and adaptations have been proposed to address specific use cases and improve efficiency.

### 6. Integration into Standard Libraries and Programming Languages

As computing became more widespread, binary search found its way into standard libraries and programming languages. It became a foundational tool for developers working with sorted data structures, arrays, and other collections.

### 7. Continued Relevance

Despite its ancient roots, the binary search algorithm remains relevant in modern computer science and software development. Its logarithmic time complexity makes it particularly valuable for efficiently searching large datasets, and it continues to be taught in introductory computer science courses.

## Comparison with Other Search Algorithms

While comparing search algorithms, the time complexity of binary search distinguishes it as a highly efficient method. Binary search operates with a remarkable time complexity of O(log n), significantly outperforming linear search algorithms with O(n) time complexity. The logarithmic nature of binary search time complexity ensures swift access to elements by halving the search space in each iteration. This efficiency is especially notable for large datasets.

The worst case complexity of binary search occurs when the target element is at an extremity or absent, resulting in a time complexity analyzed through the recurrence relation T(n) = T(n/2) + 1. In contrast, linear search exhibits linear time complexity (O(n)), making it less efficient for extensive datasets. Understanding the time complexities of these algorithms is crucial for selecting the optimal approach based on the specific dataset size and characteristics.

## Variations of Binary Search

Several variations of the binary search algorithm exist, each tailored to specific scenarios, addressing nuances in binary search complexity and time complexity for binary search. One such variant is the Interpolation Search, which adapts to datasets with non-uniformly distributed values, potentially reducing the O(log n) complexity.

Another variation, Exponential Search, combines binary and linear search elements, optimizing for scenarios where the target is closer to the dataset’s beginning, impacting the time complexity for binary search.

These adaptations acknowledge the need to address the worst case time complexity of binary search when the target is at an extremity. While these variations maintain the core principles of binary search algorithm complexity, they showcase the algorithm’s flexibility in accommodating diverse dataset characteristics and optimizing time and space complexity of binary search in specific contexts.

## Benefits of Binary Search Algorithm

It offers numerous benefits, some of which are: –

• ### Efficiency

Binary search dramatically reduces the comparisons required to find a target element within a sorted dataset. This efficiency is especially noticeable when dealing with large datasets, as the algorithm divides the search space in half with each iteration, resulting in a time complexity of O(log n). This is significantly faster than linear search algorithms with an O(n) time complexity.

• ### Fast Retrieval

Binary search complexity suits applications requiring quick data retrieval from sorted collections. Its logarithmic time complexity ensures rapid access to elements even in vast datasets, making it a valuable tool for databases, search engines, and other information retrieval systems.

• ### Predictable Performance

The performance of time complexity for binary search is consistent and predictable regardless of the size of the dataset. This reliability makes it a preferred choice when response time is crucial.

• ### Optimal for Sorted Data

Binary search is designed specifically for sorted data. When the data is sorted, the algorithm’s effectiveness shines, allowing optimal utilization of the sorted order.

• ### Simplicity

The core concept of binary search time complexity is straightforward: compare the target value with the middle element and narrow down the search range based on the comparison. This simplicity makes it relatively easy to implement and understand.

• ### Reduced Comparison Count

Binary search minimized the number of comparisons required to locate a target, resulting in improved efficiency and reduced computational load compared to linear search algorithms.

• ### Applicability to Various Data Structures

While commonly associated with arrays, the time complexity of binary search can be applied to other data structures, such as binary search trees and certain types of graphs, enhancing its versatility.

• ### Memory Efficiency

The binary search typically requires minimal additional memory beyond the existing data structure, making it memory-efficient and suitable for resource-constrained environments.

• ### Search Failure Indication

If the algorithm concludes without finding the target, it indicates that the target element is not present in the dataset. This can be useful in decision-making processes.

## Algorithmic Optimizations

Algorithmic optimizations play a crucial role in enhancing the efficiency and addressing the complexity of the binary search algorithm. To optimize the time complexity of binary search, adaptive strategies can be used, allowing early exits or intelligent decision-making during the search process. Additionally, considering the worst case time complexity of binary search, specialized algorithms may be implemented to handle edge cases more efficiently.

A focus on reducing the space complexity of binary search involves minimizing additional memory usage beyond the existing data structure. These optimizations, while maintaining the core principles of what is binary search, contribute to refined binary search algorithm complexity and elevate its performance in scenarios where traditional implementations may face challenges.

By strategically addressing complexities, these optimizations contribute to the continued relevance and applicability of the binary search algorithm.

Working of a Binary Search Algorithm

The first thing to note is that a binary search algorithm always works on a sorted list. Hence the first logical step is to sort the list provided. After sorting, the median of the list is checked with the desired value.

• If the desired value is equal to the central index’s worth, then the index is returned as an answer.
• If the target value is lower than the central index’s deal of the list, then the list’s right side is ignored.
• If the desired value is greater than the central index’s value, then the left half is discarded.
• The process is then repeated on shorted lists until the target value is found.

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Example #1

Let us look at the algorithm with an example. Assume there is a list with the following numbers:

1, 15, 23, 7, 6, 14, 8, 3, 27

Let us take the desired value as 27. The total number of elements in the list is 9.

The first step is to sort the list. After sorting, the list would look something like this:

1, 3, 6, 7, 8, 14, 15, 23, 27

As the number of elements in the list is nine, the central index would be at five. The value at index five is 8. The desired value, 27, is compared with the value 8. First, check whether the value is equal to 8 or not. If yes, return index and exit.

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As 27 is greater than 8, we would ignore the left part and only traverse the list’s right side. The new list to traverse is:

14, 15, 23, 27

Note: In practice, the list is not truncated. Only the observation is narrowed. So, the “new list” should not be confused as making a new list or shortening the original one. Although it could be implemented with a new list, there are two problems. First, there will be a memory overhead. Each new list will increase the space complexity. And second, the original indexes need to be tracked on each iteration.

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The new central index can be taken as the second or third element, depending on the implementation. Here, we will consider the third element as central. The value 23 is compared with value 27. As the value is greater than the central value, we will discard the left half.

The list to traverse is:

27

As the list contains only a single element, it is considered to be the central element. Hence, we compare the desired value with 27. As they match, we return the index value of 27 in the original list.

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Example #2

In the same list, let us assume the desired value to be 2.

First, the central value eight is compared with 2. As the desired value is smaller than the central value, we narrow our focus down to the list’s left-hand side.

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The new traversal will consist of:

1, 3, 6, 7

Let us take the central element as the second element. The desired value two is compared with 3. As the value is still smaller, we again narrow the focus down to the list’s left-hand side.

The new traversal will consist of:

1

As the traversing list has only one element, the value is directly compared to the remaining element. We see that the values do not match. Hence, we break out of the loop with an error message: value not found.

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## Practical Tips for Implementation

Implementing the binary search algorithm effectively involves considering key factors to optimize its performance and address the complexity of binary search. Firstly, understanding what is the time complexity of the binary search algorithm is essential. With a time complexity of O(log n), it excels in scenarios with large datasets. To mitigate the binary search worst case time complexity, developers can implement early exit strategies, breaking out of the search loop when conditions indicate that the target is not present. This avoids unnecessary iterations and enhances efficiency.

Considering data characteristics is crucial. For sorted datasets, binary search is optimal. Developers should ensure that the dataset remains sorted, or consider alternative search algorithms for unsorted data. Practical tips for space complexity of binary search include favoring the iterative method, which maintains a space complexity of O(1) compared to the recursive method’s O(log n).

Incorporating boundary checks and validations can prevent common errors and enhance the algorithm’s robustness. Testing the implementation on diverse datasets, including edge cases, provides insights into its real-world performance. By adhering to these practical tips, developers can harness the strengths of the binary search algorithm while minimizing complexities and ensuring efficient outcomes in various scenarios.

## Practical Tips for Implementation

Implementing the binary search algorithm effectively involves considering key factors to optimize its performance and address the complexity of binary search. Firstly, understanding what is the time complexity of the binary search algorithm is essential. With a time complexity of O(log n), it excels in scenarios with large datasets. To mitigate the binary search worst case time complexity, developers can implement early exit strategies, breaking out of the search loop when conditions indicate that the target is not present. This avoids unnecessary iterations and enhances efficiency.

Considering data characteristics is crucial. For sorted datasets, binary search is optimal. Developers should ensure that the dataset remains sorted, or consider alternative search algorithms for unsorted data. Practical tips for space complexity of binary search include favoring the iterative method, which maintains a space complexity of O(1) compared to the recursive method’s O(log n).

Incorporating boundary checks and validations can prevent common errors and enhance the algorithm’s robustness. Testing the implementation on diverse datasets, including edge cases, provides insights into its real-world performance. By adhering to these practical tips, developers can harness the strengths of the binary search algorithm while minimizing complexities and ensuring efficient outcomes in various scenarios.

## Time and Space complexity

People often do not have an understanding of binary search worst case and best case. The time complexity of the binary search algorithm is O(log n). The best-case time complexity would be O(1) when the central index would directly match the desired value. Binary search algorithm time complexity worst case differs from that. The worst-case scenario could be the values at either the extremity of the list or those not on the list.

In the worse case binary search algorithm complexity, the values are present in such a way that either they are at the extremity of the list or are not present in the list at all. Below is a brief description of how to find worse case complexity of the binary search

The equation T(n)= T(n/2)+1 is known as the recurrence relation for binary search.

To perform time complexity of binary search analysis, we apply the master theorem to the equation and get O(log n).

Worse case complexity of the binary search is often easier to compute but carries the drawback of being too much pessimistic.

On the other hand, another type of  time complexity of binary search analysis, which is binary search algorithm average complexity, is a rarely chosen measure. As it is harder to compute and requires an in-depth knowledge of how much input has been distributed, people tend to avoid binary search algorithm average complexity.

Below are the basic steps to performing Binary Search.

1. Find the mid element of the whole array, as it would be the search key.
2. Look at whether or not the search key is equivalent to the item in the middle of the interval and return an index of that search key.
3. If the value of the middle item in the interval is more than the search key, reduce the interval’s lower half.
4. If the opposite, then lower the upper half.
5. Repeat from point 2, until the value is found or the interval gets empty.

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The space complexity of the binary search algorithm depends on the implementation of the algorithm. There are two ways of implementing it:

1. Iterative method
2. Recursive method

Both methods are quite the same, with two differences in implementation. First, there is no loop in the recursive method. Second, rather than passing the new values to the next iteration of the loop, it passes them to the next recursion. In the iterative method, the iterations can be controlled through the looping conditions, while in the recursive method, the maximum and minimum are used as the boundary condition.

In the iterative method, the space complexity would be O(1). While in the recursive method, the space complexity would be O(log n).

## Limitations and Edge Cases

While the binary search algorithm is highly efficient in many scenarios, it does have limitations, particularly concerning its worst-case time complexity. The binary search worst case time complexity occurs when the target element is either located at an extremity of the sorted list or is absent altogether. In such situations, the algorithm performs suboptimally, approaching a linear search-like time complexity.

Edge cases also reveal certain limitations. For instance, when dealing with datasets that are frequently changing or unsorted, the overhead of maintaining a sorted order can outweigh the benefits of binary search. Additionally, the algorithm may exhibit unexpected behavior when handling duplicate elements. Depending on the implementation, it may return the first, last, or any arbitrary occurrence of a duplicate value, which can impact the reliability of search results.

Understanding these limitations and edge cases is crucial for selecting the appropriate search algorithm based on the specific characteristics of the dataset. While binary search excels in sorted datasets, consideration of its constraints is necessary to make informed algorithmic choices in various real-world scenarios.

## Evolution of Binary Search

The evolution of the binary search algorithm reflects a journey from ancient manual techniques to its formalization in computer science, showcasing its adaptability and continued relevance. The basic concept of binary search, dividing a sorted dataset to locate a target efficiently, has ancient roots in manual search methods, like those used in manuscripts or books. In the mid-20th century, binary search found its place in electronic computing.

Notably, John Mauchly employed binary search on the ENIAC in 1946, marking an early application in computing history. Derrick Henry Lehmer’s 1948 paper further formalized the algorithm’s description in the context of electronic computers. As computing advanced, binary search became integral to sorting and searching libraries and found its way into standard programming languages. The algorithm’s logarithmic time complexity made it invaluable for efficient searches in large datasets.

Ongoing research and analysis have led to a deeper understanding of its complexities, with adaptations and optimizations addressing specific use cases. Today, the evolution of binary search continues, with ongoing research exploring improvements, adaptations, and its integration into emerging technologies. Its enduring presence in computer science underscores its foundational role in algorithmic solutions and highlights its capacity to evolve with the changing landscape of technology.

## Interactive Examples or Visualizations

Improve understanding of the binary search algorithm with interactive examples or visualizations. These aids provide an intuitive understanding of its step-by-step process, aiding users in understanding the algorithm’s intricacies. Visualize the dataset, highlighting how binary search divides it in half during each iteration. Incorporate interactive elements, allowing users to input target values and witness the algorithm’s path to the solution. Such visual aids not only make the learning experience engaging but also reinforce the principles of binary search in a dynamic and accessible manner, promoting a deeper understanding of its functionality.

## Benefits

• binary search algorithm is a fairly simple search algorithm to implement.
• It is a significant improvement over linear search and performs almost the same in comparison to some of the harder to implement search algorithms.
• The binary search algorithm breaks the list down in half on every iteration, rather than sequentially combing through the list. On large lists, this method can be really useful.

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## Conclusion

binary search algorithm is a widely used algorithm in the computational domain. It is a fat and accurate search algorithm that can work well on both big and small datasets. A binary search algorithm is a simple and reliable algorithm to implement. With time and space analysis, the benefits of using this particular technique are evident.

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#### Rohit Sharma

Blog Author
Rohit Sharma is the Program Director for the UpGrad-IIIT Bangalore, PG Diploma Data Analytics Program.
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#### Data Science Skills to Master

1Is it true that linear search is superior to binary search?

If you just need to search once, linear search will surely be faster than sorting followed by binary search if the data is originally unsorted. Binary search, on the other hand, is recognized to be a considerably quicker method of searching than linear search. Binary search allows you to remove half of the remaining items at a time, whereas linear search would go through each element one by one.

2What distinguishes interpolation search from binary search?

Interpolation search is a binary search-like technique for finding a specified target value in a sorted array. It's similar to how people search through a phone book for a certain name, with the target value used to sort the book's contents. To check, binary search always travels to the center element. Interpolation searching, on the other hand, may lead to various places depending on the value of the key being searched for. If the key's value is closer to the final element, for example, interpolation search is more likely to begin at the end.

3Is it better to do a recursive binary search or an iterative binary search?

The recursive version of Binary Search has a space complexity of O(log N), but the iterative version has a space complexity of O(log N) (1). As a result, while the recursive version is simple to build, the iterative form is more efficient.

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