2025-07-31 07:28:31 +0000 UTC

class Solution:
    def calPoints(self, operations: List[str]) -> int:
        stack = []
        stack_sum = 0
        for op in operations:
            if op.isnumeric() or op.startswith("-"):
                new_score = int(op)
                stack.append(new_score)
                stack_sum += new_score
            elif op == "+":
                new_score = stack[-1] + stack[-2]
                stack_sum += new_score
                stack.append(new_score)
            elif op == "D":
                new_score = stack[-1] * 2
                stack_sum += new_score
                stack.append(new_score)
            elif op == "C":
                stack_sum -= stack[-1]
                stack.pop()
            else:
                raise Exception(op)
        return stack_sum