Serial/Sequential Algorithm

A serial algorithm (also called a sequential algorithm) is an algorithm that performs its operations one after another in a single sequence — without any parallelism or concurrency.

Characteristics of a Serial Algorithm:

• Executes one instruction at a time.
• Runs on a single processor/core.
• Each step depends on the result of the previous step.
• Easier to understand and debug.
• Used when parallelism is unnecessary or would add complexity.

Examples of Serial Algorithms with Pseudocode

1. Sum of Elements in an Array

function sumArray(arr)
    total = 0
    for i from 0 to length of arr - 1
        total = total + arr[i]
    return total

• Type: Linear, serial
• Time Complexity: O(n)

2. Find Maximum in an Array

function findMax(arr)
    max = arr[0]
    for i from 1 to length of arr - 1
        if arr[i] > max
            max = arr[i]
    return max

• Type: Linear, serial
• Time Complexity: O(n)

3. Linear Search

function linearSearch(arr, target)
    for i from 0 to length of arr - 1
        if arr[i] == target
            return i
    return -1

• Type: Linear search, serial
• Time Complexity: O(n)

4. Bubble Sort

function bubbleSort(arr)
    for i from 0 to length of arr - 1
        for j from 0 to length of arr - i - 2
            if arr[j] > arr[j + 1]
                swap arr[j] and arr[j + 1]

• Type: Sorting, serial
• Time Complexity: O(n²)

5. Counting Even Numbers

function countEvens(arr)
    count = 0
    for i from 0 to length of arr - 1
        if arr[i] mod 2 == 0
            count = count + 1
    return count

• Type: Linear, serial
• Time Complexity: O(n)

When to Use Serial Algorithms

• When the dataset is small or operations are inexpensive.
• When the problem is inherently sequential (e.g., reading a book line by line).
• When hardware only supports single-threaded execution.