Linear Search in Python

 

In this python post, you will learn the following:

• What is a Linear Search?
• Linear Search Algorithm
• Write a Python Program For Linear Search Using While Loop
• Write a Python Program For Linear Search Using For Loop
• Linear Search in Python Program using Recursion

What is a Linear Search?

First of all, A linear search, also known as a sequential search, this method is used to find an element within a list or array. It checks each element of the list one by one / sequentially until a match is found or the whole list has been searched.

Linear Search Algorithm

Implement linear search following the below steps:

• Traverse the list/array using a loop.
• In every iteration, associate the target value with the given value of the list/array.
  • If the values match, return the current index of the list/array.
  • Otherwise, move on to the next array/list element.
• If no match is found, return -1.

Write a Python Program For Linear Search Using While Loop

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# python program for linear search using while loop   #define list lst = []   #take input list size num = int(input("Enter size of list :- "))   for n in range(num):     #append element in list/array     numbers = int(input("Enter the array of %d element :- " %n))     lst.append(numbers)   #take input number to be find in list   x = int(input("Enter number to search in list :- "))   i = 0 flag = False   while i < len(lst):     if lst[i] == x:         flag = True         break        i = i + 1    if flag == 1:     print('{} was found at index {}.'.format(x, i)) else:     print('{} was not found.'.format(x))

After executing the program, the output will be:

Enter size of list :-  5
Enter the array of 0 element :-  10
Enter the array of 1 element :-  23
Enter the array of 2 element :-  56
Enter the array of 3 element :-  89
Enter the array of 4 element :-  200
Enter number to search in list :-  89
89 was found at index 3.

Write a Python Program For Linear Search Using For Loop

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# python program for linear search using for loop   #define list lst = []   #take input list size num = int(input("Enter size of list :- "))   for n in range(num):     #append element in list/array     numbers = int(input("Enter the array of %d element :- " %n))     lst.append(numbers)   #take input number to be find in list   x = int(input("Enter number to search in list :- "))   i = 0 flag = False   for i in range(len(lst)):     if lst[i] == x:         flag = True         break    if flag == 1:     print('{} was found at index {}.'.format(x, i)) else:     print('{} was not found.'.format(x))

After executing the program, the output will be:

Enter size of list :-  6
Enter the array of 0 element :-  25
Enter the array of 1 element :-  50
Enter the array of 2 element :-  100
Enter the array of 3 element :-  200
Enter the array of 4 element :-  250
Enter the array of 5 element :-  650
Enter number to search in list :-  200
200 was found at index 3.

Linear Search in Python Program using Recursion

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# python program for linear search using for loop   #define list lst = []   #take input list size num = int(input("Enter size of list :- "))   for n in range(num):     #append element in list/array     numbers = int(input("Enter the array of %d element :- " %n))     lst.append(numbers)   #take input number to be find in list   x = int(input("Enter number to search in list :- "))   # Recursive function to linear search x in arr[l..r]  def recLinearSearch( arr, l, r, x):     if r < l:         return -1     if arr[l] == x:         return l     if arr[r] == x:         return r     return recLinearSearch(arr, l+1, r-1, x)         res = recLinearSearch(lst, 0, len(lst)-1, x)    if res != -1:     print('{} was found at index {}.'.format(x, res)) else:     print('{} was not found.'.format(x))

After executing the program, the output will be:

Enter size of list :-  5
Enter the array of 0 element :-  14
Enter the array of 1 element :-  25
Enter the array of 2 element :-  63
Enter the array of 3 element :-  42
Enter the array of 4 element :-  78
Enter number to search in list :-  78
78 was found at index 4.