C#•15mo ago

❔ ✅ Basic Tic Tac Toe Checker that uses a 2-D Array

The question says this: This time, you have to write only a checker for the game. It will be a method that takes a 2D array and returns a boolean. If there is a winner, it returns true otherwise false. We use "X" and "O" as signs of our players. The empty places will be filled with numbers from 1 to 9. You have to check 3 types of cases: horizontal; vertical; diagonal; The answer to the code is:

namespace Coding.Exercise
{
    public class TicTacToe
    {
        public static bool Checker(string[,] board)
        {
            // here we perform horizontal and vertical checks
            for (int i = 0; i < 3; i++)
            {
                if (board[i,0] == board[i,1] && board[i,1] == board[i,2])
                    return true;
                if (board[0,i] == board[1,i] && board[1,i] == board[2,i])
                    return true;
            }
            // here diagonal checks 
            if (board[0,0] == board[1,1] && board[1,1] == board[2,2])
                return true;
            if (board[0,2] == board[1,1] && board[1,1] == board[2,0])
                return true;
            return false;
        }
    }
}

namespace Coding.Exercise
{
    public class TicTacToe
    {
        public static bool Checker(string[,] board)
        {
            // here we perform horizontal and vertical checks
            for (int i = 0; i < 3; i++)
            {
                if (board[i,0] == board[i,1] && board[i,1] == board[i,2])
                    return true;
                if (board[0,i] == board[1,i] && board[1,i] == board[2,i])
                    return true;
            }
            // here diagonal checks 
            if (board[0,0] == board[1,1] && board[1,1] == board[2,2])
                return true;
            if (board[0,2] == board[1,1] && board[1,1] == board[2,0])
                return true;
            return false;
        }
    }
}

My answer to the code is this:

38 Replies

krixsick•15mo ago

namespace Coding.Exercise
{
    public class TicTacToe
    {
        public static bool Checker(string[,] board)
        {
            
            for (int i = 0; i < board.GetLength(0); i++)
            {
                for (int j = 0; j < board.GetLength(1); j++)
                {
                    if(board[i,0] == board[i,1] && board[i,1] == board[i,2])
                    {
                        return true;
                    }
                    else if(board[0,j] == board[1,j] && board[1,j] == board[2,j]){
                        return true;
                    }
                    else if(i == j){
                        return true;
                    }
                    //diagonal 
                    else if(board[0,2] == board[1,1] && board[1,1] == board[2,0]){
                        return true;
                    }
                    else{
                        return false;
                    }

                    
                }
            }
     
        }
    }
}

namespace Coding.Exercise
{
    public class TicTacToe
    {
        public static bool Checker(string[,] board)
        {
            
            for (int i = 0; i < board.GetLength(0); i++)
            {
                for (int j = 0; j < board.GetLength(1); j++)
                {
                    if(board[i,0] == board[i,1] && board[i,1] == board[i,2])
                    {
                        return true;
                    }
                    else if(board[0,j] == board[1,j] && board[1,j] == board[2,j]){
                        return true;
                    }
                    else if(i == j){
                        return true;
                    }
                    //diagonal 
                    else if(board[0,2] == board[1,1] && board[1,1] == board[2,0]){
                        return true;
                    }
                    else{
                        return false;
                    }

                    
                }
            }
     
        }
    }
}

I was wondering if anyone could help me identify how my code is wrong or why the answer code only used for (int i = 0; i < 3; i++) and not a nested for loop to access the elements inside the 2-D array

cap5lut•15mo ago

1) else if(i == j): if noone won using the coordinate 0, 0, this is check results in true, basically on the first iteration 2) ur diagonal check checks only only one diagonal, but there are 2 diagonals in a square, u are missing the 0,0 -> 1,1 -> 2,2 diagonal 3) else { return false; } lets assume 1) didnt exist and u would reach this point at this point u have checked the horizontal line, the vertical line and (lets assume 2) is fixed) the diagonal lines for 0,0 if anyone would have won in a line not involving 0,0 u then here return a false negative and breaking the loops and return from the method 4) this one is not an error resulting in a wrong result, but a logical one: with these 2 nested loops u iterate over each cell of the board, and check each line. basically at 0,0 u test for 0,0 -> 0,1 -> 0,2 for 0,1 u test for 0,0 -> 0,1 -> 0,2 for 0,2 u test for 0,0 -> 0,1 -> 0,2 as well, so its ending up in redundant checks (this happens vertical, horizontal and for one diagonal right now) on how about to reach the answer's code ill get to in ~5min need a quick smoke back, so can u follow so far, or do u have any questions?

krixsick•15mo ago

Oh thank you so much for the feedback, I get everything just expect for the last part, by for 0,2 u test for 0,0 -> 0,1 -> 0,2 My thought process was that that for loops would function like this, so it first does [0, j] and j gets looped 3 times, resulting in [0,0], [0,1], [0,2] Then it goes back to the outer loop and goes back to the inner loop again, resulting in [1,0], [1,1], [1,2]

cap5lut•15mo ago

yeah, so with just the loop iterations (outer and inner combined) u basically visit every cell right?

krixsick•15mo ago

Yea

cap5lut•15mo ago

so for every cell u have this check: if(board[i,0] == board[i,1] && board[i,1] == board[i,2]) for example

krixsick•15mo ago

Yes OH because if its true does the for outer loop reset? wait Nvm i think Im wrong

cap5lut•15mo ago

basically with that if u check if the column i is a win column, right?

krixsick•15mo ago

Yea Cause the i variable should be the same throughout So if its the same, it'll create a line of the same value making it considered a win i think

cap5lut•15mo ago

but u check it for all cells, thus u check it for all cells of that column as well,

krixsick•15mo ago

Ohh So im just constantly checking even if it does return something

cap5lut•15mo ago

lets strip ur loops a bit down:

for (int i = 0; i < 1; i++)
{
  for (int j = 0; j < 3; j++)
  {
    if(board[i,0] == board[i,1] && board[i,1] == board[i,2])
    {
      return true;
    }
  }
}

for (int i = 0; i < 1; i++)
{
  for (int j = 0; j < 3; j++)
  {
    if(board[i,0] == board[i,1] && board[i,1] == board[i,2])
    {
      return true;
    }
  }
}

krixsick•15mo ago

Wait then my diagonal checks should be outside the for loops cause looking back that doesn't make sense

cap5lut•15mo ago

note that i is only 0 in that stripped down code

krixsick•15mo ago

Ohh So it never goes to 1 or 2

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❔ ✅ Basic Tic Tac Toe Checker that uses a 2-D Array