Python: Check if there are duplicate values in a given flat list

Last update on April 19 2025 13:00:44 (UTC/GMT +8 hours)

Check Duplicates in List

Write a Python program to check if there are duplicate values in a given flat list.

Use set() on the given list to remove duplicates, compare its length with the length of the list.

Sample Solution:

Python Code:

# Define a function named 'has_duplicates' to check if a list has duplicate values.
# It takes a single parameter, 'lst', which is the list to be checked.
def has_duplicates(lst):
    # Check if the length of the list is not equal to the length of the set of the list.
    # If the lengths are not equal, there are duplicates in the list.
    return len(lst) != len(set(lst))

# Create a list of numbers and check for duplicates.
nums = [1, 2, 3, 4, 5, 6, 7]
print("Original list:")
print(nums)
# Check if there are duplicate values in the given list using the 'has_duplicates' function.
print("Check if there are duplicate values in the said given flat list:")
print(has_duplicates(nums))

# Create another list with duplicate values and check for duplicates.
nums = [1, 2, 3, 3, 4, 5, 5, 6, 7]
print("\nOriginal list:")
print(nums)
# Check if there are duplicate values in the given list using the 'has_duplicates' function.
print("Check if there are duplicate values in the said given flat list:")
print(has_duplicates(nums))

Sample Output:

Original list:
[1, 2, 3, 4, 5, 6, 7]
Check if there are duplicate values in the said given flat list:
False

Original list:
[1, 2, 3, 3, 4, 5, 5, 6, 7]
Check if there are duplicate values in the said given flat list:
True

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to list all duplicate elements found in a flat list.
Write a Python program to count duplicate elements and return a dictionary mapping each duplicate to its frequency.
Write a Python program to check for duplicates in a list without using extra data structures.
Write a Python program to remove duplicates from a list and return both the cleaned list and the duplicates that were removed.

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