Python Coding Challenge - Question with Answer (ID -280326)

 

🔹 1. Importing reduce

from functools import reduce

reduce() is a function from the functools module.

It applies a function cumulatively to the items of a sequence.

It reduces the list to a single value.

🔹 2. Defining the List

data = [1, 2, 3]

A simple list with 3 elements.

reduce() will process these elements one by one.

🔹 3. Understanding the Lambda Function

lambda x, y: y - x

This is an anonymous function.

It takes two arguments:

x → accumulated value (previous result)

y → next element in the list

Important: It calculates y - x (not x - y) → this is the tricky part ⚠️

🔹 4. How reduce() Works Internally

reduce() applies the function like this:

👉 Step 1:

x = 1, y = 2

Compute: y - x = 2 - 1 = 1

👉 New result = 1

👉 Step 2:

x = 1 (previous result), y = 3

Compute: y - x = 3 - 1 = 2

👉 Final result = 2

🔹 5. Final Output

print(result)

✅ Output:

2

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