Knowledge test

I did a knowledge test where I received a link with 3 steps, unfortunately, I stayed stucked at second step.

The first step ask for to get te middle char of any word.
If the word has a even length, return 2 middle digits otherwise, the middle digit.

Solution

public static string GetMiddle(string s)
{
  if(s.Length <= 2) return s;

  var isEven = s.Length % 2 == 0;

  // I remove 1 digit because de array is 0 index;
  // I always round up for de odd words, even words the division is exact
  // rounding up odd words, i dont need to handle with even/odd on the 1 subtraction
  var middleDigit = (int)Math.Ceiling(s.Length * 1M / 2M) - 1;

  return s.Substring(middleDigit, isEven ? 2 : 1);
}

At this point, everything is ok.

---

The second step asked to me for count the notes of an ATM dispenser just with notes of values: 100, 50 and 20.

Withdrawals

• $260
• $40
• $230
• $250

Outputs

• {2, 0, 3}
• {0, 0, 2}
• {1, 1, 4}
• {2, 1, 0}

Solution

public static int[] Withdraw(int amount)
{
  var result = new int[] { 0,0,0 };

  var note100Result = (int)Math.Floor(amount * 1M / 100M);

  if(note100Result > 0)
  {
    var remainValue = amount - (note100Result * 100);

    if(remainValue % 50 !=0)
      if(remainValue % 20 !=0)
        note100Result--;

    result[0] = note100Result;

    if(note100Result > 0)
      amount -= note100Result * 100;
  }

  var note50Result = (int)Math.Floor(amount * 1M / 50M);

  if(note50Result > 0)
  {
    var remainValue = amount - (note50Result * 50);

    if(remainValue % 20 !=0)
      note50Result--;

    result[1] = note50Result;

    if(note50Result > 0)
      amount -= note50Result * 50;
  }

  var note20Result = (int)Math.Floor(amount * 1M / 20M);

  if(note20Result > 0)
  {
    result[2] = note20Result;
  }

  return result;
}

The logic is: you just can proceed to another note if the remaining value is fully divisible for ANY ONE of the other notes, otherwise,
you need to subtract 1 note of the current note counter.

Of course, this can be done in other ways, with a loop and Linq as example, but I preferred to do like this to be more explainable.

---

As I didn't finish the second step, I even couldn't see the third step :(

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As I said earlier, I stayed stucked at this step. I did this test after a long day of work, so my brain was not okay to do tasks like this.

My tip for this tests:

• Do this in a unstressed moment, after take a snap or a good sleep night (if you can choice this moments obviously)