Isogram detector (Python with regex)

Question

I have tried to solve this problem with reg. expressions but when there is any repetition give false when it should come true. Can anyone help me?

import re
x=input()

y=r"([a-z])?"
if re.search(x,y):
print ("true")
else:
print ("false")

Answer 1

Can you please give example inputs since it is not clear what exactly the problem is?

Answer 2

Ok. Objective: detect words without any of the letters repeated. Example: come(0 letters repetead), sololearn(o and l are repeted).

Answer 3

Try this:

word=input()
list_word=list(word)
n=0
while n < len(list_word):
if list_word.count(list_word[n]) == 1:
n+=1
else:
break
if n==len(list_word):
print ("true")
else:
print ("false")

Answer 4

import re
s=input().lower()
pattern=r'([a-z]).*\1'
if re.search(pattern,s):
print('false')
else:
print('true')