PYTHON

finding duplicate characters in a string python

#finds duplicate characters
def duplicatecharacters(s:str):
    for i in s:
        if s.count(i)>1:
            return True
    return False
print(duplicatecharacters(""))

count repeated characters in a string python

# Python 3+
import collections
collections.Counter(input_string)

# Python 2 or custom results.
{key: string.count(key) for key in set(string)}

# Other ways are too slow. In the source, You can see the proves.