Linear Search Algorithm in Python - programminginpython.com

Hello everyone, welcome back to programminginpython.com! Here I am going to explain to you how to implement linear search algorithm in python. This linear search is a basic search algorithm which searches all the elements in the list and finds the required value. This is also known as sequential search.

Here in this technique, I compare each and every element with the key element to be found, if both of them matches, the algorithm returns that element is found and its position.

You can also watch the video on YouTube here

Program on Github

Code Visualization – Linear Search Algorithm

Time Complexity

Best Case	O(1)
Average Case	O(n)
Worst Case	O(n)

Program on Github

Algorithm

Given a list L of n elements with values or records,L0 ... Ln-1 and key/target element K, linear search is used to find the index/position of the target K in list L

Initialize a boolean variable found and set it to False initially
Start for loop with i ranging from 0 to the length of the list
Check if key element is equal to L[i]
1. if equals
  1. set found boolean variable to True
  2. print the position of the element found
  3. break for loop
If the boolean variable found is equal to False after for loop, print that the element is not found in the list

Program on Github

Program

__author__ = 'Avinash'

lst = []
num = int(input("Enter size of list: \t"))
for n in range(num):
    numbers = int(input("Enter any number: \t"))
    lst.append(numbers)

x = int(input("\nEnter number to search: \t"))

found = False

for i in range(len(lst)):
    if lst[i] == x:
        found = True
        print("\n%d found at position %d" % (x, i))
        break
if not found:
    print("\n%d is not in list" % x)

__author__ = 'Avinash'

lst = []

num = int(input("Enter size of list: \t"))

for n in range(num):

numbers = int(input("Enter any number: \t"))

lst.append(numbers)

x = int(input("\nEnter number to search: \t"))

found = False

for i in range(len(lst)):

if lst[i] == x:

found = True

print("\n%d found at position %d" % (x, i))

break

if not found:

print("\n%d is not in list" % x)

Program on Github

Output

Linear Search Algorithm - programminginpython.com — Linear Search Algorithm – programminginpython.com

Same algorithm in other programming languages

In C language: http://www.mycodingcorner.com/2015/01/c-linear-search.html

In CPP language: http://www.mycodingcorner.com/2015/03/cpp-program-for-implementing-linear-search-technique.html

In Java language: http://www.mycodingcorner.com/2015/01/java-linear-search.html