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Question 20

What is the output of the following code? [3 marks]

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inbox = [9, 2, 5, 0, 0, 4, 3, 3, 0, 1, 8, 7, 0]
outbox = tuple()
temp = []

for item in inbox:
    if item != 0:
        temp.append(item)
    elif len(temp) != 0:
        smallest = temp[0]
        for comp in temp[1:]:
            smallest = min(smallest, comp)

        outbox = outbox + (smallest,)
        temp.clear()

print(outbox)
Solution

Initialize inbox to be a list with integers 9, 2, 5, 0, 0, 4, 3, 3, 0, 1, 8, 7, 0. Variables outbox and temp are an empty tuple and list respectively.

Trace the program flow by iterating through each element in inbox.

item item != 0? New temp len(temp) != 0? smallest comp New smallest: min(smallest, comp) New outbox
9 True [9]
2 True [9, 2]
5 True [9, 2, 5]
0 False [9, 2, 5] True 9 2 min(9, 2) = 2
2 5 min(2, 5) = 2 () + (2,) = (2,)
0 False [] False
4 True [4]
3 True [4, 3]
3 True [4, 3, 3]
0 False [4, 3, 3] True 4 3 min(4, 3) = 3
3 3 min(3, 3) = 3 (2,) + (3,) = (2, 3)
1 True [1]
8 True [1, 8]
7 True [1, 8, 7]
0 False [1, 8, 7] True 1 8 min(1, 8) = 1
1 7 min(1, 7) = 1 (2, 3) + (1,) = (2, 3, 1)
Answer 
(2, 3, 1)