Python Coding Challenge - Question with Answer (ID -120626)

 

Code Explanation:

Line 1: x = [[]] * 2

What happens?

[] creates an empty list.

[[]] creates a list containing one empty list.

* 2 duplicates the reference to the inner list, not the list itself.

Memory Representation

x

│

├──► []

└──► []

Both x[0] and x[1] point to the same inner list.

Value of x

[[], []]

Line 2: x[0].append(1)

What happens?

x[0] refers to the shared inner list.

append(1) adds 1 to that list.

Memory Representation

x

│

├──► [1]

└──► [1]

Since both positions reference the same list, both appear updated.

Value of x

[[1], [1]]

Line 3: print(x)

What happens?

Python prints the contents of x.

Output

[[1], [1]]

Why This Happens

List Multiplication (*)

x = [[]] * 2

creates:

x[0] ──┐

        ├──► []

x[1] ──┘

Both elements point to the same list object.

Final Output

[[1], [1]]