Python Program for Linear Search

Problem: Given an array arr[] of n elements, write a function to search a given element x in arr[].
Examples :

Input : arr[] = {10, 20, 80, 30, 60, 50, 
                     110, 100, 130, 170}
          x = 110;
Output : 6
Element x is present at index 6

Input : arr[] = {10, 20, 80, 30, 60, 50, 
                     110, 100, 130, 170}
           x = 175;
Output : -1
Element x is not present in arr[].

A simple approach is to do linear search, i.e

Start from the leftmost element of arr[] and one by one compare x with each element of arr[]
If x matches with an element, return the index.
If x doesn’t match with any of elements, return -1.

Example:

# Searching an element in a list/array in python 
# can be simply done using \'in\' operator 
# Example: 
# if x in arr: 
#   print arr.index(x) 
  
# If you want to implement Linear Search in python 
  
# Linearly search x in arr[] 
# If x is present then return its location 
# else return -1 
  
def search(arr, x): 
  
    for i in range(len(arr)): 
  
        if arr[i] == x: 
            return i 
  
    return -1

The time complexity of above algorithm is O(n).

Please refer complete article on Linear Search for more details!

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