Answer: Python Puzzler #1379

The answer is C. The program prints:

53

Why?

The loop remembers the biggest number it has seen so far, and replaces it whenever it finds a bigger one. This is how computers find the maximum.

Trace table

A trace table follows the program step by step. Here’s this one:

n	n > biggest?	biggest
18	yes	18
40	yes	40
3	no	40
53	yes	53
11	no	53

The code again

numbers = [18, 40, 3, 53, 11]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)