Python Coding challenge - Day 549| What is the output of the following Python Code?

Code Explanation:

Line 1: Importing reduce

from functools import reduce

This imports the reduce() function from the functools module.

reduce() repeatedly applies a function to elements of a list, reducing the list to a single result.

Line 2: Creating the list

lst = [1, 2, 3, 4]

This defines a list lst with integers: [1, 2, 3, 4].

You will process this list using reduce() to get the squares of even numbers only.

Line 3–7: Using reduce() to build the result

res = reduce(

    lambda acc, x: acc + [x**2] if x % 2 == 0 else acc,

    lst, []

)

Explanation of reduce(function, iterable, initializer):

Function:

lambda acc, x: acc + [x**2] if x % 2 == 0 else acc

acc is the accumulator (starts as an empty list []).

x is the current element from the list.

If x is even (x % 2 == 0), add its square (x**2) to the accumulator.

If x is odd, return the accumulator unchanged.

Iterable: lst = [1, 2, 3, 4]

Initializer: []

Start with an empty list.

Line 8: Print the result

print(res)

[4, 16]

Final Result:

This code returns a list of squares of even numbers from the input list [1, 2, 3, 4].

Even numbers: 2, 4

Their squares: 4, 16

Output: [4, 16]

Final Output:

[4,16]

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