Answer: Python Puzzler #1574

The answer is C. The program prints:

57

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
50	yes	50
35	no	50
57	yes	57
4	no	57
30	no	57

The code again

numbers = [50, 35, 57, 4, 30]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)