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Problem: Baseball Game

Explore how to use a stack to efficiently manage and calculate scores in a baseball game with special rules. Learn to apply push, pop, and peek operations to track valid scores and handle operations like doubling and summing recent scores. This lesson helps you understand stack usage for last-in, first-out data processing and optimize the solution with linear time complexity.

Statement

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

You are given a list of string operations, where each operations[i] represents theithi^{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.

Note: The test cases are constructed such that the final answer and all intermediate calculations fit within a 3232‑bit integer, and all operations are guaranteed to be valid.

Constraints:

  • 11 \leq ...