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 s = "",

    time = await readline();

  for (let i = 0; i < time; i++) {

    let line = await readline();

    if (typeof line == "string") {

      if (line[0] == 1) {

        s += line.split(" ")[1];

      } else if (line[0] == 2) {

        s = s.substring(0, s.length);

      } else if (line[0] == 3) {

        console.log(s[line.split(" ")[1]]);

      } else if (line[0] == 4) {

        let s1 = s.substring(0, +line.split(" ")[1]+1);

        s = s.slice(+line.split(" ")[1]+1);

        s = s1 + line.split(" ")[2] + s;

      } else if (line[0] == 5) {

        s = s.split("").sort().join("");

      } else if (line[0] == 6) {

        s = s

          .split("")

          .sort((a, b) => b - a)

          .join("");

      } else if (line[0] == 7) {

        console.log(s.length);

      } else if (line[0] == 8) {

        console.log(s.split("").join(" "));

      }

    }

  }

})();