Andy, Ben and Charlotte are playing a board game. The three of them decided to come up with a new scoring system. A player's first initial ("A", "B" or "C") denotes that player scoring a single point. Given a string of capital letters, return a list of the players' scores.
For instance, if ABBACCCCAC is written when the game is over, then Andy scored 3 points, Ben scored 2 points, and Charlotte scored 5 points, since there are 3 instances of letter A, 2 instances of letter B, and 5 instances of letter C. So the list [3, 2, 5] should be returned.
calculate_scores("A") ➞ [1, 0, 0]
calculate_scores("ABC") ➞ [1, 1, 1]
calculate_scores("ABCBACC") ➞ [2, 2, 3]
If given an empty string as an input, return [0, 0, 0].