C#•2y 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

krixsickOP•2y 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•2y 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?

krixsickOP•2y 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•2y ago

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

krixsickOP•2y ago

Yea

cap5lut•2y ago

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

krixsickOP•2y ago

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

cap5lut•2y ago

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

krixsickOP•2y 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•2y ago

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

krixsickOP•2y ago

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

cap5lut•2y 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;
    }
  }
}

krixsickOP•2y ago

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

cap5lut•2y ago

note that i is only 0 in that stripped down code

krixsickOP•2y ago

Ohh So it never goes to 1 or 2

cap5lut•2y ago

nah, thats not what i mean u do the check inside the inner loop, for j = 0 to 2, but u dont even use j there, because u check the whole column so u could basically do the check outside of the inner loop:

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

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

and it would still check for the ith column

krixsickOP•2y ago

Ohh For this part: else if(board[0,j] == board[1,j] && board[1,j] == board[2,j]){ return true; It would make sense for it to be underneath the inner loop right?

cap5lut•2y ago

yeah, there u would only need the inner loop, as u do not care about i there

krixsickOP•2y ago

Ohh I see

cap5lut•2y ago

so for columns u dont need the inner, and for rows not the outer loop, so for this part u dont even need nesting:

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

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

krixsickOP•2y ago

Ohh I see Ohh the nested loop I created is good to access ALL the elements inside the 2-D arrays

cap5lut•2y ago

yes, all one by one

krixsickOP•2y ago

but for this purpose it's just inefficient and won't work Ohhh I see Omg Thank you so much for the clarification and help!

cap5lut•2y ago

well, it is inefficient yes, but u could make it work ^^

krixsickOP•2y ago

Got it, gonna try to redo this again Thank you again!

cap5lut•2y ago

glad i could help 🙂 good luck with ur new implementation, if u get stuck just ask here again (or if u r done and everything works fine u can then also $close this thread)

MODiX•2y ago

Use the /close command to mark a forum thread as answered

krixsickOP•2y ago

Thanks! Will definitely ask here again if that's fine with you lol, but again Thank you!

cap5lut•2y ago

ofc, thats what this thread is for!

krixsickOP•2y ago

Ok, I think I finished it, this is my new version:

using System;

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

using System;

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

Again I know I probably said this, but I seriously want to thank you for your help in helping me understand what I did wrong

cap5lut•2y ago

looking good ;p and now think about ur two for loops, basically they do the same thing, iterating from 0 to 2

krixsickOP•2y ago

Oh you're right Then there's no point of having another, since it's just used to check but not storing actual values If it did stored values in a list then an additional loop would be necessary right?

cap5lut•2y ago

combining the loops to one would change the order of checks. so in this use case it doesnt matter, while in others it might do and the rest is more or less just syntactic differences to provided answer u couldnt understand at first ;p

if (a) {
  return true;
}
else {
  return false;
}

if (a) {
  return true;
}
else {
  return false;
}

and

if (a) {
  return true;
}
return false;

if (a) {
  return true;
}
return false;

⤴️ is basically the same

krixsickOP•2y ago

Ohhh got it thank you so much!

cap5lut•2y ago

glad i could help 😄 dont forget to $close the thread

MODiX•2y ago

Use the /close command to mark a forum thread as answered

krixsickOP•2y ago

Oh Yea thanks for the reminder Hope you have a great day and again thank you! !close

Accord•2y ago

Closed! Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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