题解 | #【模板】栈#

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void (async function () {
    //记录操作次数
    const n = await readline();
    //定义一个栈
    const stack = [];
    for (let i = 0; i < n; i++) {
        //获取输入
        const input = await readline();
        //转换为操作数组
        const action = input.split(" ");
        //如果为push操作，并且有操作数，则入栈
        if (action[0] === "push" && action[1]) {
            stack.push(parseInt(action[1]));
        } else if (action[0] === "pop") {
            //pop操作
            console.log(stack[stack.length - 1] ? stack.pop() : "error");
        } else if (action[0] === "top") {
            console.log(
                stack[stack.length - 1] ? stack[stack.length - 1] : "error"
            );
        }
    }
})();