Find Unique Characters in a File

Question

I have a file with 450,000+ rows of entries. Each entry is about 7 characters in length. What I want to know is the unique characters of this file.

For instance, if my f

Answer 1

Print unique characters (ASCII and Unicode UTF-8)

import codecs
file = codecs.open('my_file_name', encoding='utf-8')

# Runtime: O(1)
letters = set()

# Runtime: O(n^2)
for line in file:
  for character in line:
    letters.add(character)

# Runtime: O(n)
letter_str = ''.join(letters)

print(letter_str)

Save as unique.py, and run as python unique.py.