What Is Merging Operation in Data Structure?


Scott Campbell

In data structure, the merging operation refers to the process of combining two or more data structures into a single structure. This operation is particularly useful when dealing with sorted lists or arrays. By merging two sorted lists or arrays, we can create a new sorted list or array that contains all the elements from both original structures.

Why Do We Need the Merging Operation

The merging operation is commonly used in various algorithms and applications. It allows us to efficiently combine multiple sorted lists or arrays into a single sorted structure. This can be beneficial in many scenarios, such as:

  • Merging two lists of customer orders to generate a consolidated report
  • Combining multiple sorted arrays to perform efficient searching and sorting operations
  • Merging multiple log files to analyze system performance

How Does the Merging Operation Work

To understand how the merging operation works, let’s consider an example of merging two sorted arrays:

Array A: [1, 3, 5, 7]
Array B: [2, 4, 6]

In this case, we want to merge Array A and Array B into a new sorted array. To achieve this, we can follow these steps:

  1. Create a new empty array C to store the merged result.
  2. Initialize two pointers: one for Array A (pointer A) and one for Array B (pointer B).
  3. Compare the elements at pointers A and B.
    • If the element at pointer A is smaller than the element at pointer B, add it to array C and move pointer A forward.
    • If the element at pointer B is smaller than the element at pointer A, add it to array C and move pointer B forward.
  4. Repeat step 3 until either pointer A reaches the end of Array A or pointer B reaches the end of Array B.
  5. If there are remaining elements in Array A or Array B, add them to array C.
  6. The resulting array C will now contain all the elements from both arrays, sorted in ascending order: [1, 2, 3, 4, 5, 6, 7].

Time and Space Complexity

The time complexity of the merging operation depends on the size of the input data structures. In the case of merging two sorted arrays/lists with n and m elements respectively, the time complexity is O(n + m). This is because we need to compare each element from both arrays/lists exactly once.

The space complexity of the merging operation is O(n + m) as well. We need to allocate additional memory for storing the merged result. However, this can be improved by using an in-place merging algorithm that avoids extra memory allocation.


The merging operation plays a crucial role in various data structure algorithms and applications. By understanding how this operation works and its time and space complexity, we can utilize it effectively in our programs.

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