Merge Sort Algorithm in Python

In this source code example, we will write a code to implement the Merge Sort algorithm in Python.

Merge sort is one of the most efficient sorting algorithms. With a time complexity of O(n log n), it’s one of the fastest of all general-purpose sorting algorithms. The idea behind merge sort is divide and conquer — to break a big problem into several smaller, easier-to-solve problems, and then combine those solutions into a final result. The merge sort mantra is to split first and merge after.

Merge Sort Algorithm in Python

In this Python program, we will take input from the User or console and print the result to the output:
def merge_sort(collection: list) -> list:

    def merge(left: list, right: list) -> list:

        def _merge():
            while left and right:
                yield (left if left[0] <= right[0] else right).pop(0)
            yield from left
            yield from right

        return list(_merge())

    if len(collection) <= 1:
        return collection
    mid = len(collection) // 2
    return merge(merge_sort(collection[:mid]), merge_sort(collection[mid:]))


if __name__ == "__main__":
    user_input = input("Enter numbers separated by a comma:\n").strip()
    unsorted = [int(item) for item in user_input.split(",")]
    print(*merge_sort(unsorted), sep=",")

Output:

Enter numbers separated by a comma:
20,15,5,10,3,2,1
1,2,3,5,10,15,20

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