题解 | 【模板】序列操作

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

void (async function () {
    // Write your code here

    let lin_nums = [];

    while (true) {
        let line = await readline();
        if (line === undefined) break;
        lin_nums.push(line.trim());
    }

    let ans_arr = []; 

    for (let i = 0; i < lin_nums.length; i++) {
        let tokens = lin_nums[i].split(" "); 
        let op = tokens[0];
        let param1 = tokens[1] ? +tokens[1] : null; 
        let param2 = tokens[2] ? +tokens[2]: null; 

        switch (op) {
            case "1": 
                if (!isNaN(param1)) ans_arr.push(param1);
                break;
            case "2": 
                if (ans_arr.length > 0) ans_arr.pop();
                break;
            case "3": 
                if (!isNaN(param1) && param1 >= 0 && param1 < ans_arr.length) {
                    console.log(ans_arr[param1]);
                }
                break;
            case "4": 
                if (
                    !isNaN(param1) &&
                    !isNaN(param2) &&
                    param1 >= 0 &&
                    param1 <= ans_arr.length
                ) {
                    ans_arr.splice(param1 + 1, 0, param2); 
                }
                break;
            case "5": 
                ans_arr.sort((a, b) => a - b);
                break;
            case "6": 
                ans_arr.sort((a, b) => b - a);
                break;
            case "7": 
                console.log(ans_arr.length);
                break;
            case "8": 
                console.log(ans_arr.join(" "));
                break;
        }
    }

    while ((line = await readline())) {
        let tokens = line.split(" ");
        let a = parseInt(tokens[0]);
        let b = parseInt(tokens[1]);
        console.log(a + b);
    }
})();