What Is Divide and Conquer in Data Structure and Algorithm?


Larry Thompson

What Is Divide and Conquer in Data Structure and Algorithm?

In the world of computer science, divide and conquer is a powerful algorithmic technique used to solve complex problems efficiently. It involves breaking down a problem into smaller subproblems, solving them independently, and then combining the results to obtain the final solution. This approach is widely applied in various algorithms and data structures to optimize their performance.

The Three Steps of Divide and Conquer

The divide and conquer technique follows three essential steps:

  1. Divide: The problem is divided into smaller subproblems. This step requires careful consideration to identify the best way to break down the problem so that each subproblem can be solved independently.
  2. Conquer: Each subproblem is solved independently by applying the same algorithm recursively or iteratively until it becomes simple enough to solve directly.
  3. Combine: The solutions of the subproblems are combined to obtain the final solution of the original problem.

An Example: Merge Sort

To better understand divide and conquer, let’s take a look at one of its most popular applications: merge sort. Merge sort is an efficient sorting algorithm that follows the divide and conquer approach.

Step 1: Divide

In merge sort, the divide step involves dividing an array into two halves until each half contains only one element. This recursive division process continues until we have multiple single-element subarrays.

Step 2: Conquer

In this step, we apply merge sort algorithmically to sort each individual element by comparing pairs of single-element subarrays and merging them in ascending order. This process continues until we merge all the subarrays, resulting in a sorted array.

Step 3: Combine

The final step of merge sort involves merging the sorted subarrays to obtain a fully sorted array. This is done by repeatedly comparing the elements of the subarrays and merging them in ascending order.

The Advantages of Divide and Conquer

Divide and conquer offers several advantages:

  • Easier Problem Solving: By breaking down a complex problem into smaller, more manageable subproblems, divide and conquer makes it easier to develop algorithms and data structures.
  • Improved Efficiency: Divide and conquer allows us to solve problems more efficiently by reducing their time complexity. Each subproblem is solved independently, potentially utilizing parallelism, resulting in faster overall execution.
  • Code Reusability: Since divide and conquer follows a recursive approach, it promotes code reusability. The same algorithm can be applied recursively to solve multiple instances of the problem.


The divide and conquer technique is a fundamental concept in computer science that helps us tackle complex problems with efficiency and elegance. By dividing problems into smaller subproblems, solving them independently, and combining the results, we can obtain optimal solutions for various algorithms and data structures. Understanding divide and conquer opens up a world of possibilities for solving challenging computational tasks.

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