 # 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:

### 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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