So, I was trying to solve some coding problems and came across this one:
Question:
Xenia the beginner mathematician is a third-year student at elementary school. She is now learning the addition operation.
The teacher has written down the sum of multiple numbers. Pupils should calculate the sum. To make the calculation easier, the sum only contains numbers 1, 2 and 3. Still, that isn't enough for Xenia. She is only beginning to count, so she can calculate a sum only if the summands follow in non-decreasing order. For example, she can't calculate sum 1+3+2+1 but she can calculate sums 1+1+2 and 3+3.
You've got the sum that was written on the board. Rearrange the summans and print the sum in such a way that Xenia can calculate the sum.
Input The first line contains a non-empty string s — the sum Xenia needs to count. String s contains no spaces. It only contains digits and characters "+". Besides, string s is a correct sum of numbers 1, 2 and 3. String s is at most 100 characters long.
Output Print the new sum that Xenia can count.
So basically if I input 3+2+1, the output should be 1+2+3.
My solution was basically removing the '+', sorting a list, and then use the join function. The problem is that my code does not remove the '+'. I tried iteration with pop and delete and simply using the remove function but nothing works.
Here is my code:
a=input()
for i in range(0,len(list(a))):
if list(a)[i]=='+':
list(a).pop(i)
b=[int(x) for x in list(a)]
b.sort()
print('+'.join(list(a)))
I tried printing at every step and the problem is that the "+" is not removed. Please help.
ERROR MSG: ValueError: invalid literal for int() with base 10: '+'
[this means that the '+' was not removed]
