Code to output the first repeated character in given string?

Question

I'm trying to find the first repeated character in my string and output that character using python. When checking my code, I can see I'm not index the last character of my code.

What am I doing wrong?

letters = 'acbdc'
for a in range (0,len(letters)-1):
#print(letters[a])
    for b in range(0, len(letters)-1):
        #print(letters[b])
        if (letters[a]==letters[b]) and (a!=b):
            print(b)
            b=b+1
a=a+1

Answer 1

You can do this in an easier way:

letters = 'acbdc'
found_dict = {}
for i in letters:
    if i in found_dict:
        print(i)
        break
    else:
        found_dict[i]= 1

Output: c

Answer 2

Here's a solution with sets, it should be slightly faster than using dicts.

letters = 'acbdc'
seen = set()

for letter in letters:
    if letter in seen:
        print(letter)
        break
    else:
        seen.add(letter)