CODEWITHSUNDEEP
python
TheLearner
TheLearner

Reputation: 103

Why does my Python codes give output with multiple lines?

I am a Python beginner and started my journey by solving some Code Forces problems.

I faced some problems when trying to write Python codes for this question: https://codeforces.com/problemset/problem/339/A

Basically, the input row contains a string with numbers and '+', e.g. '3 + 2 + 1', and the codes must convert the string into a series in ascending order and print as output, e.g. output '1 + 2 + 3' from '3 + 2 + 1'.

This is my attempt:

lines = (sys.stdin.readlines())
answer = ''
arranged = []
intermediate = str((lines)[0]).split('+')
arranged += [intermediate[0]]
k = 1
i = 0
for k in range(1, len(intermediate)):
    while i < len(arranged) and intermediate[k] > arranged[i]:
        i += 1
    arranged[i:i] = [intermediate[k]]
for item in arranged:
    answer += item + '+'
print(answer[:-1])

When I ran the codes using custom test, it works: giving out '1 + 2 + 3' as output.

However, when I submitted my answer, the output was given as 

1
+ 2 + 3

making my codes fail in first test.

Attached image to show what I meant:

enter image description here

What's wrong?

Upvotes: 0

Views: 137

Answers (2)

Y.R.
Y.R.

Reputation: 391

The problem is that readlines() captures a blank line (\n) that is attached to '1'.

Consider this solution, using 'strip' to remove the unwanted \n:

intermediate = str((lines)[0]).strip().split('+')

In this case a debug print would have been really useful. By printing 'intermediate', the result is:

['3', '2', '1\n']

And you could have easily detected your problem.

Upvotes: 1

Milan Cermak
Milan Cermak

Reputation: 8064

I think readlines() captures a newline character \n that's "attached" to the 1 when you do the split. You can use the strip function to remote leading and trailing whitespace characters.

Upvotes: 1

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