使用Map来进行存储key值唯一 然后通过sort来拍下输出

const readline = require("readline");

const r = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
});
const lines = [];
r.on("line", function (line) {
  lines.push(line);
  if (lines.length - 1 === parseInt(lines[0])) {
    lines.shift();

    const t = new Map();
    lines.forEach((item) => {
      const [index, value] = item.split(" ");
      const exitValue = t.get(index);
      if (exitValue) {
        t.set(index, exitValue + parseInt(value));
      } else {
        t.set(index, parseInt(value));
      }
    });
    const b = Array.from(t).sort((a, b)=> {
        return parseInt(a[0]) - parseInt(b[0])
    })
    b.forEach((item) => {
      console.log(item[0] + ' ' + item[1]);
    });
  }
});

Object版本 通过获取key值然后key值相同叠加，通过index排序输出

const readline = require("readline");

const r = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
});
const lines = [];
r.on("line", function (line) {
  lines.push(line);
  if (lines.length - 1 === parseInt(lines[0])) {
    lines.shift();

    const t = {};
    lines.forEach((item) => {
      const [index, value] = item.split(" ");
      const exitValue = t[index];
      if (exitValue) {
        t[index] = exitValue + parseInt(value);
      } else {
        t[index] = parseInt(value);
      }
    });
    const c = Object.keys(t).sort((a, b) => {
      return parseInt(a) - parseInt(b);
    });
    c.forEach((item) => {
      console.log(item + " " + t[item]);
    });
  }
});