Question

I was given this problem

Given an int array length 3, if there is a 2 in the array immediately followed by a 3,
set the 3 element to 0.
For Example ({1, 2, 3}) → {1, 2, 0}
({2, 3, 5}) → {2, 0, 5}
({1, 2, 1}) → {1, 2, 1}

And this is my implementation.

int[] x = { 1, 2, 1 };
            for (int i = 0; i < x.Length; i++)
            {
                if (x[i] == 2 && x[i + 1] == 3)
                {

                    for (int j = 0; j < x.Length; j++)
                    {
                        if (x[j]==3)
                        {
                            x[j] = 0;
                        }
                    }

                }
            }

            foreach (int i in x)
            {
                Console.Write(i);
            }

I got zero as result. Can you help me to find where I am at mistake. I can’t figure it out because the lecturer didn’t gave any explanation in details.

Answer 1

You do not need all these loops: with the length of 3, you need to perform only two checks, like this:

if (x[0]==2 && x[1]==3) x[1] = 0;
if (x[1]==2 && x[2]==3) x[2] = 0;

For arrays of arbitrary size, you could use a single loop:

for (var i = 0 ; i < x.Length-1 ; i++) {
    if (x[i]==2 && x[i+1]==3) x[i+1] = 0;
}