Python Program to Find Two Odd Occurring Elements in an Array/List

In the previous article, we have discussed Python Program to Count Words that Appear Exactly Two Times in an Array/List of Words
Counter function in Python:

The counter is a set and dict subset. Counter() takes an iterable entity as an argument and stores the elements as keys and the frequency of the elements as a value. So, in collections, if we transfer a string. When you call Counter(), you’ll get a Counter class object with characters as keys and their frequency in a string as values.

Counter() returns a Counter type object (a subclass of dict) with all characters in the string as keys and their occurrence count as values. We’ll use the [] operator to get the occurrence count of the characters from it.

Given a list, and the task is to find two odd occurring elements in a given list.

Examples:

Example1:

Input:

Given list = [5, 2, 3, 2, 3, 4, 6, 4]

Output:

The Two odd Occuring elements in a given list [5, 2, 3, 2, 3, 4, 6, 4] are :
5 6

Example2:

Input:

Given list = [2, 1, 2, 3, 1, 2, 3, 5, 5, 6]

Output:

The Two odd Occuring elements in a given list [2, 1, 2, 3, 1, 2, 3, 5, 5, 6] are :
2 6

Program to Find Two Odd Occurring Elements in an Array/List in Python

Below are the ways to find two odd occurring elements in a given list:

Using Counter Function (Static Input)
Using Counter Function (User Input)

Method #1: Using Counter Function (Static Input)

Approach:

Import the Counter() function from collections using the import keyword.
Give the list as static input and store it in a variable.
Calculate the frequency of all the given list elements using the Counter() function which returns the element and its frequency as key-value pair and store this dictionary in another variable (say lstfreqelements).
Traverse in this frequency dictionary using the for loop.
Inside the loop, check if any Key has the value odd using the if conditional statement.
If the statement is true, then print the key for getting the two odd occurring elements in a given list.
The Exit of the program.

Below is the implementation:

# Import the Counter() function from collections using the import keyword.
from collections import Counter
# Give the list as static input and store it in a variable.
gvn_lst = [5, 2, 3, 2, 3, 4, 6, 4]
# Calculate the frequency of all the given list elements using the Counter() function
# which returns the element and its frequency as key-value pair and
# store this dictionary in another variable (say lstfreqelements).
lstfreqelements = Counter(gvn_lst)
print("The Two odd Occuring elements in a given list", gvn_lst, "are :")
# Traverse in this frequency dictionary using the for loop.
for key in lstfreqelements:
    # Inside the loop, check if any ley has the value odd using the if conditional statement.
    if lstfreqelements[key] % 2 != 0:
        # If the statement is true, then print the key for getting the two odd occurring elements
        # in a given list.
        print(key, end=" ")

Output:

The Two odd Occuring elements in a given list [5, 2, 3, 2, 3, 4, 6, 4] are :
5 6

Method #2: Using Counter Function (User Input)

Approach:

Import the Counter() function from collections using the import keyword.
Give the list as user input using list(),map(),input(),and split() functions.
Store it in a variable.
Calculate the frequency of all the given list elements using the Counter() function which returns the element and its frequency as key-value pair and store this dictionary in another variable (say lstfreqelements).
Traverse in this frequency dictionary using the for loop.
Inside the loop, check if any key has the value odd using the if conditional statement.
If the statement is true, then print the key for getting the two odd occurring elements in a given list.
The Exit of the program.

Below is the implementation:

# Import the Counter() function from collections using the import keyword.
from collections import Counter
# Give the list as user input using list(),map(),input(),and split() functions. 
# Store it in a variable.
gvn_lst = list(map(int, input(
   'Enter some random List Elements separated by spaces = ').split()))
# Calculate the frequency of all the given list elements using the Counter() function
# which returns the element and its frequency as key-value pair and
# store this dictionary in another variable (say lstfreqelements).
lstfreqelements = Counter(gvn_lst)
print("The Two odd Occuring elements in a given list", gvn_lst, "are :")
# Traverse in this frequency dictionary using the for loop.
for key in lstfreqelements:
    # Inside the loop, check if any ley has the value odd using the if conditional statement.
    if lstfreqelements[key] % 2 != 0:
        # If the statement is true, then print the key for getting the two odd occurring elements
        # in a given list.
        print(key, end=" ")

Output:

Enter some random List Elements separated by spaces = 2 1 2 3 1 2 3 5 5 6
The Two odd Occuring elements in a given list [2, 1, 2, 3, 1, 2, 3, 5, 5, 6] are :
2 6

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