CS50 Problem Set 3: Why is my code failing check50 for the grocery problem?

Question

The problem set I am trying to solve: CS50P 2022 psets/3/grocery/

My code:

def main():

    lst = []
    try:
        while True:
            lst.append(input().upper())
    except EOFError:
        pass
    lst.sort()
    grocery = [[lst[0], 1]]

    for item in lst[1:]:
        if item.upper() != grocery[-1][0]:
            grocery.append([item.upper(), 1])
        else:
            grocery[-1][1] += 1

    for item in grocery:
        print(f'{item[1]} {item[0]}')
    return

main()

The Check50 results:

:) grocery.py exists

:( input of EOF halts program
Cause
expected exit code 0, not 1

Log
running python3 grocery.py...
sending EOF...
checking that program exited with status 0...
:| input of "apple" and "banana" yields "1 APPLE 1 BANANA"
Cause
can't check until a frown turns upside down

:| input of "strawberry" and "strawberry" yields "2 STRAWBERRY"
Cause
can't check until a frown turns upside down

:| input of "mango", "sugar", and "mango" yields "2 MANGO 1 SUGAR"
Cause
can't check until a frown turns upside down

:| input of "tortilla" and "sweet potato" yields "1 SWEET POTATO 1 TORTILLA"

The issue seems to lie here:

:( input of EOF halts program
Cause
expected exit code 0, not 1

I have tried different ways of coding this problem, and although in testing I always get the right output, I always fail this Check50 test.

I am having trouble understanding how to make this work. Please help.

Answer 1

Here:

def main():
    lst = []
    try:
        while True:
            lst.append(input().upper())
    except EOFError:
        pass 

If the input consists of just an EOF (no other input), your code simply passes on the EOFError and lst will still be the empty list []. So, the code will fail on [lst[0] and exit with an error code here:

    lst.sort()
    grocery = [[lst[0], 1]]

Instead of just passing, you probably want to return or exit in case lst is still the empty list. Add a simple if to the except section, like this:

def main():
    lst = []
    try:
        while True:
            lst.append(input().upper())
    except EOFError:
        if lst == []:
            exit()
        else:
            pass