freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-javascript/68e39ed6106dac2f0a98fd66.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
68e39ed6106dac2f0a98fd66	Challenge 84: Infected	28	challenge-84

--description--

On November 2nd, 1988, the first major internet worm was released, infecting about 10% of computers connected to the internet after only a day.

In this challenge, you are given a number of days that have passed since an internet worm was released, and you need to determine how many computers are infected using the following rules:

• On day 0, the first computer is infected.
• Each subsequent day, the number of infected computers doubles.
• Every 3rd day, a patch is applied after the virus spreads and reduces the number of infected computers by 20%. Round the number of patched computers up to the nearest whole number.

For example, on:

• Day 0: 1 total computer is infected.
• Day 1: 2 total computers are infected.
• Day 2: 4 total computers are infected.
• Day 3: 8 total computers are infected. Then, apply the patch: 8 infected * 20% = 1.6 patched. Round 1.6 up to 2. 8 computers infected - 2 patched = 6 total computers infected after day 3.

Return the number of total infected computers after the given amount of days have passed.

--hints--

infected(1) should return 2.

assert.equal(infected(1), 2);

infected(3) should return 6.

assert.equal(infected(3), 6);

infected(8) should return 152.

assert.equal(infected(8), 152);

infected(17) should return 39808.

assert.equal(infected(17), 39808);

infected(25) should return 5217638.

assert.equal(infected(25), 5217638);

--seed--

--seed-contents--

function infected(days) {

  return days;
}

--solutions--

function infected(days) {
  let infected = 1;

  for (let day = 1; day <= days; day++) {
    infected *= 2;

    if (day % 3 === 0) {
      let patched = Math.ceil(infected * 0.2);
      infected -= patched;
    }
  }

  return infected;
}