Python Data Structure and Algorithm Tutorial – Linear Search

Linear Search


In this tutorial, you will learn about linear search. Also, you will find working examples of linear search in Python.

Linear search is the simplest searching algorithm that searches for an element in a list in sequential order. We start at one end and check every element until the desired element is not found.

How Linear Search Works?

The following steps are followed to search for an element k = 1 in the list below.

Initial array
Array to be searched for
  1. Start from the first element, compare k with each element x.
    Element not found
    Compare with each element
  2. If x == k, return the index.
    Element found
    Element found
  3. Else, return not found.

Linear Search Algorithm

LinearSearch(array, key)
  for each item in the array
    if item == value
      return its index

Python Examples

/* Linear Search in Python */

def linearSearch(array, n, x):

    /* Going through array sequentially */
    for i in range(0, n):
        if (array[i] == x):
            return i
    return -1

array = [2, 4, 0, 1, 9]
x = 1
n = len(array)
result = linearSearch(array, n, x)
if(result == -1):
    print("Element not found")
    print("Element found at index: ", result)

Linear Search Complexities

Time Complexity: O(n)

Space Complexity: O(1)

Linear Search Applications

  1. For searching operations in smaller arrays (<100 items).


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