Problem: Baseball Game

Statement

You are the scorekeeper for a baseball game with unusual rules. You begin with an empty score record.

You are given an array of strings operations, where each operations[i] represents the $i^{th}$operation to apply to the record. Each operation is one of the following:

• An integer x: Record a new score of x.

• "+": Record a new score equal to the sum of the two most recent scores.

• "D": Record a new score equal to double the most recent score.

• "C": Invalidate and remove the most recent score from the record.

Return the sum of all scores remaining on the record after all operations have been applied. ...