for example from a random input number by using input() i want to remove only a single number 5

note: if multiple 5's are there only 1 five should be removed, from left to right

examples:

1. input = 555, output should be 55
2. input = 599657, output should be 59967
3. input = 6578, output should be 678
4. input = 59959786, output should be 5999786
5. input = 34567, output should be 3467
6. input = 55, output should be 5

CodePudding user response：

Potentially split at the rightmost 5, then join back:

s = input()
print(''.join(s.rsplit('5', 1)))

Or reverse the string so we can use replace and then reverse back:

s = input()
print(s[::-1].replace('5', '', 1)[::-1])

CodePudding user response：

Find the index of the right most 5, if it exists. Then slice the string, excluding that position

s = input()
i = s.rfind("5")
if i == -1:
    print(s)
else:
    print(s[:i]   s[i 1:])

CodePudding user response：

Pretty sure it is not the best idea, but here we go:

def removeLast5(number):
  string = str(number)
  reverseList = list(reversed(list(string)))
  check =False
  for index, chr in enumerate(reverseList):
    if chr == "5":
      check = True
      break
  if check:
    del reverseList[index]
  return "".join(reversed(reverseList))

If you run the function such as removeLast5(425674345) you will get 42567434 as a result.

CodePudding user response：

To do it using math only (i.e. without converting to string), you could make a recursive function:

def removeLast5(N):
    return removeLast5(N//10)*10 N if N and N != 5 else N//10

for n in (555,599657,6578,59959786,34567,55):
     print(n,"-->",removeLast5(n))

555 --> 55
599657 --> 59967
6578 --> 678
59959786 --> 5999786
34567 --> 3467
55 --> 5

If you're processing this as a string, you could use a regular expression with re.sub:

import re
N = input() 
print( re.sub(r"5(?!.*5)",'',N) ) # replace 5 not followed by another 5