This is the solution that made me look into constant vs linear time complexity and consider that I should learn formulas. Very interesting and never something I would have checked out otherwise

a more simple question, can you give comments on how this solution works? Thanks~!

I'm not understanding how this works. How am I misunderstanding?

using System.Linq;

public class Kata
{
public static object FirstNonConsecutive(int[] arr)
{
//create a variable count and set it equal to the value of the first index in arr a.k.a arr[0]

    var count = arr.First();

    //loop through each item in the arr array
    
    foreach (var val in arr)
    {   
        //if the val in the arr doesn't equal the first val in arr, return the val
        //my understanding is that count is == arr[0]
        //so on the first iteration of the loop, the if statment condition isn't met
        //on the second iteration, they will likely not be equal.
        //but the fact that the two indicies aren't equal doesn't mean that they are also no consecutive. 
        
        /
        if (val != count)
        {
            return val;
        }
        count++;
    }
    return null;
}

}

PS I know this answer is correct, I'm not challenging that. I just want help to understand how it works. Thanks if you see this!

I just started c# (and coding) recently and am trying to work on 8 kyu stuff. Glad I wasn't crazy here and thanks for the reply!

I believe you are actually correct. This should have failed some test cases similar to the one you posted. To be fair to myself, I wrote this close to 5 years ago or so. Because of this, I just took another stab at it and this is how I would approach this today. No need to loop:

https://www.codewars.com/kata/reviews/57f615994f267f2f4d0000ea/groups/63923fa39321de00015a762c

int[] numbers = {3,4,3,3,3};

What if the second index holds the stray? Wouldn't this solution assume that if [0] & [1] are different, that [0] is the stray? With the above array for example. The first if statement compares index 0 and 1, they are different, so it assigns val to index [0].