Baseball Game - https://leetcode.com/problems/baseball-game/

baseball-game.cs

public class Solution {
    public int CalPoints(string[] ops) {
        var score = new List<int>();

        for (int i = 0; i < ops.Length; i++)
        {
            string c = ops[i];

            if (c == "+")
            {
                score.Add(score[^1] + score[^2]);
            }
            else if (c == "D")
            {
                score.Add(score[^1] * 2);
            }
            else if (c == "C")
            {
                score.RemoveAt(score.Count - 1);
            }
            else
            {
                score.Add(int.Parse(c));
            }
        }

        return score.Sum();
    }
}

Testcase:

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Run Code Result: