Yandex Contest how to get rid of Memory Limit/Time Limit error?

Question

JavaScript

There is the following task: yandex contest
There are 2 solutions:

//Решение 1:
const fs = require('fs');
const readline = require('readline');

const rl = readline.createInterface({
  input: fs.createReadStream('input.txt'),
  terminal: false
});

let prev;

rl.once('line', () => {
  rl.on('line', line => {
    if (line != prev) fs.appendFileSync('output.txt', `${prev ? '\n' : ''}${prev = line}`);
  });
});

//Решение 2:
const fs = require('fs');
const readline = require('readline');

const rl = readline.createInterface({
  input: fs.createReadStream('input.txt'),
  terminal: false
});

let prev;

rl.once('line', () => {
  rl.on('line', line => {
    if (line != prev) process.stdout.write(`${prev ? '\n' : ''}${prev = line}`);
  });
});

The problem of the 1st solution is the time limit (1s) is exceeded, and the second is the memory limit (20 MB). How can this code be optimized?

Answer 1

Pseudocode

открыл файл
a = прочитал одно число
пока файл не кончился
    b = прочитал одно число
    если a < b
        вывел a
        a = b
вывел a

Answer 2

the solution actually boils down to just removing duplicates from the input array
using System;
using System.Linq;
namespace Test {
class Program {
static void Main() {
int n = Convert.ToInt32(Console.ReadLine());
int i = 0;
int[]mass = new int[n];
while (n > 0) {
mass[i] = Convert.ToInt32(Console.ReadLine());
n--; i++;
}
mass = mass.Distinct().ToArray();
GC.SuppressFinalize(n); GC.SuppressFinalize(i);
GC.Collect();
foreach (var item in mass) {
Console WriteLine(item);
}
}
}
}