Unique Character Mapping

Write a function that returns a character mapping from a word.

Examples

character_mapping("abcd") ➞ [0, 1, 2, 3]

character_mapping("abb") ➞ [0, 1, 1]

character_mapping("babbcb") ➞ [0, 1, 0, 0, 2, 0]

character_mapping("hmmmmm") ➞ [0, 1, 1, 1, 1, 1]

Notes

• Start your counter at 0, and increment by 1 each time you encounter a new character.
• Identical characters should share the same number.