 # Find the biggest number in an array challenge

Find the biggest number in an array challenge
0

#1

https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/return-largest-numbers-in-arrays/

I have done this challenge and came up with a way that it does return you a new array consists of all the biggest numbers from the sub-arrays.

But only when the numbers in it are bigger than 0.

``````function a(arr){
let result=[];
for(let i = 0;i<arr.length;i++){
let sub_arr = arr[i];

let biggest_sub=0;
for(let j=0;j<sub_arr.length;j++){

if(sub_arr[j]>biggest_sub){
biggest_sub=sub_arr[j];
}
}
result.push(biggest_sub);
}
return result;
}

console.log(a([[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], [-72, -3, -17, -10]]));

``````

how should I mod it so that negative numbers will be compared too?

#2

You can simply call Math.max() function on your array. Make sure you use spread operator because it just takes series of numbers delimited by commas.

#3

I will give it a try later. Thanks!

#4

This line is the problem. You are setting largest to 0, so if you have a sub array of negative numbers, you will end up saying the largest is 0.

#5

Hi,

A work around for this can be done declaring biggest_sub always to be the first position of the array, that way, if the array contains only negative values, it will compare the values to themselves, be aware that you’ll need to create an exception for when the array is empty.

#6
``````function a(arr){
let result=[];
for(let i = 0;i<arr.length;i++){
let sub_arr = arr[i];

if(sub_arr!==[]){
let biggest_sub=sub_arr;
for(let j=0;j<sub_arr.length;j++){

if(sub_arr[j]>biggest_sub){
biggest_sub=sub_arr[j];
}
}
result.push(biggest_sub);
}
else{return "Empty array detected.";}
}
return result;
}

console.log(a([[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], [-72, -3, -17, -10]]));

``````

is this correct?

#7

instead of iterating over each subArr with a for loop look at using the .sort() array method. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort
this way you won’t have to initialize a biggestNumberInSubArr

#8

This will always evaluate to true. Why are you trying to compare sub_arr with an empty array?

#9

so since it is always gonna be true. it is un-necessary?

@RandellDawson

#10

to further the point you cant compare arrays or objects because they pass reference and not value so will always be different

#11

I am just saying your if statement (as written) will always evaluate to true. If you really want to check if an array is empty (an edge case that is not being tested by FCC), then you would need to compare the array’s length to some value (I’ll let you figure out that value).

#12

i think you are looking for `if(sub_arr.length > 0) {...}`

#13

Well, I was trying not to just give him the answer, but yes that would work or since you already posted the answer:

``````if (sub_arr.length) {...}
``````

#14 thanks for the tip.