Baseball Game

LeetCode題目: 682. Baseball Game

My solution:

/**
 * @param {string[]} operations
 * @return {number}
 */
let calPoints = operations => {
    let stack = [];
    for(let i=0; i<operations.length; i++) {
        switch(operations[i]) {
            case 'C':
                stack.pop();
                break;
            case 'D':
                stack.push(stack.at(-1)*2);
                break;
            case '+':
                stack.push(stack.at(-2)+stack.at(-1));
                break;
            default:
                stack.push(Number(operations[i]));
        }
    }
    return stack.reduce((acc, curr) => acc + Number(curr), 0);
};