A couple of days ago I received and email from HackerRank. They invited me to solve one of their challenges soā¦ Thatās what weāre going to do now!

You are in charge of the cake for your nieceās birthday and have decided the cake will have one candle for each year of her total age. When she blows out the candles, sheāll only be able to blow out the tallest ones. Your task is to find out how many candles she can successfully blow out.

For example, if your niece is turning

4years old, and the cake will have4candles of height3,3,1,2, she will be able to blow out2candles successfully, since the tallest candles are of height3and there are such candles.

## Function description

Create a function:

`birthdayCakeCandles`

. It must return an integer representing the number of candles she can blow out.

`birthdayCakeCandles`

has the following parameter:`arr`

- an array of integers representing candleheights.

As you can see itās pretty simple, but if they challenged meā¦ I have to solve it! :smiley:

You can find the challenge on HackerRank.

**Note**: Before reading forward, Iād recommend that you solve the challenge on your own first. Than you can take a peak š on my solutions.

## First solution - the cleaner way

For this one weāre going to do a couple of steps:

- create a variable which will store the highest candle height. Letās call this variable:
`max`

- (a) loop over the array and (b) increase a
`counter`

everytime the current`item`

is equal to`max`

- if the
`item`

is higher than`max`

, reset the`counter`

and also set`max`

to be equal to the`item`

- at the end, return the
`counter`

(`item`

is the current candle height from the given `arr`

)

```
function birthdayCakeCandles(arr) {
// Step 1
let max = 0;
let counter = 0;
// Step 2 (a)
arr.forEach(item => {
// Step 3
if (item > max) {
// Step 4
max = item;
counter = 1;
// Step 2 (b)
} else if (item === max) {
counter++;
}
});
return counter;
}
```

## Second solution - the clever but not optimal way

We could also use some ātricksā to make it easier to understand the code, without having to use both `if`

and `else if`

statements.

This time letās do the following:

- use
`Math.max`

+ the`array spread`

operator to get the maximum value from the array - use the arrayās
`filter`

method to return an array with only the`max`

values - return the length of this
`filter`

ed array

```
function birthdayCakeCandles(arr) {
let max = Math.max(...arr);
return arr.filter(item => item === max).length;
}
```

Itās not the *optimal way* because are looping twice over the array (int the `Max.max`

and the `filter`

methods).

## Third solution - the one-liner

(Or the worst but most satisfying way ā¤ļø)

You might know (or if you donāt, ask my friend: **jenovs**) that I like the `reduce`

function so everytime I can, I love using it, including this time. š

Soā¦ for this one, weāre going to use a `ternary`

operator *twice* because one `ternary`

operator can only handle 2 cases at a time. Plug another one in and you can have 3 cases: š

`item`

>`max`

`item`

=`max`

`item`

<`max`

Also, the default value of the `acc`

(accumulator) would be an `object`

where weāre going to save the two values we need: `max`

and `counter`

.

Other than that we just have to use the ālogicā from the **First solution** - sort ofā¦ :wink:

- If the
`max`

is less than the`item`

we save it and reset the`counter`

. - Else if the
`item`

is equal to the`max`

we increase the counter and we spread the rest of the object (although we only have one prop and we donāt have to use the`spread`

operator. We could just re set the`max`

again, butā¦ itās nice to see the*three*dots syntax š ). - Else, just return the
`object`

And at the end, we return the `counter`

prop of the returning `object`

.

```
const birthdayCakeCandles = arr =>
arr.reduce(
(acc, item) =>
acc.max < item
? { max: item, counter: 1 }
: acc.max === item
? { ...acc, counter: ++acc.counter }
: acc,
{ max: 0, counter: 0 }
).counter;
```

## Conclusion

Thatās all we have for nowā¦ a simple problem with a simple solution. š

As always, I had fun coming up with all these solutions. Which one did you like the most?

Maybe you found another solutionā¦ Iād like to see it so let me know. You can brag about it! š