# Thread: Optimisations required for 8 queen problem.

1. ## Optimisations required for 8 queen problem.

Hello,
i posted this c# version of solution in C# board also but since c# and c are near about similar only i thought of posting it here also. Please review my logic and suggest and optimisations required in it. Also if c# version is not allowed please let me know, i will convert it into C and post it here again. I posted here since most members are active here. On c# board hardly anybody can be seen :d. Also i read on google that backtracking can reduce computations and all such things but i dont understand backtracking. Also tell me if i am using any such backtracking in my solution or not. These terms confuse me more than anything else, also i would appreciate if anybody explains me term what is heuristic approach, because i would attempt for 8 Knights problem. Thanks in advance!

Code:
```using System;

namespace EightQueen
{
public enum SIZE
{
size = 8
}
public class EightQueen
{
public static int count = 0;
public static int FunctionCalls = 0;
public static bool isValidMove(int[,] boardArr, int row, int col)
{
for (int i = 0; i < SIZE.size.GetHashCode(); i++)
if (boardArr[row,i] == 1)
return false;

for (int i = 0; i < SIZE.size.GetHashCode(); i++)
if (boardArr[i,col] == 1)
return false;
int tempCol = col + 1, tempRow = row ;

for (int i = row + 1; i < SIZE.size.GetHashCode(); i++)
{
if (tempCol < SIZE.size.GetHashCode())
{
if (boardArr[i,tempCol] == 1)
return false;
else
tempCol++;
}
else
break;
}
tempCol = col - 1;
for (int i = row - 1; i >= 0; i--)
{
if (tempCol >= 0)
{
if (boardArr[i,tempCol] == 1)
return false;
else
tempCol --;
}
else
break;
}
tempCol = col - 1;
for (int i = row + 1; i < SIZE.size.GetHashCode(); i++)
{
if (tempCol >= 0)
{
if (boardArr[i, tempCol] == 1)
return false;
else
tempCol--;
}
else
break;
}
tempCol = col + 1;
for (int i = row - 1; i >= 0; i--)
{
if (tempCol < SIZE.size.GetHashCode())
{
if (boardArr[i, tempCol] == 1)
return false;
else
tempCol++;
}
else
break;
}

return true;
}

public static void ShouldPrintBoard(int[,] boardArr)
{
int count = 0;
for (int i = 0; i < SIZE.size.GetHashCode(); i++)
for(int j = 0; j < SIZE.size.GetHashCode() ;j++)
if (boardArr[i,j] == 1)
count++;
if (count >= 8)
PrintBoard(boardArr);
}
public static void PrintBoard(int[,] boardArray)
{
for (int i = 0; i < SIZE.size.GetHashCode(); i++)
{
for (int j = 0; j < SIZE.size.GetHashCode(); j++)
Console.Write("{0} ", boardArray[i, j]);
Console.WriteLine();
}
count++;
Console.WriteLine();
}
public static void PermuteBoard(int[,] boardArr, int row, int col)
{
FunctionCalls++;
for (int i = row; i < SIZE.size.GetHashCode(); i++)
{
for (int j = 0; j < SIZE.size.GetHashCode(); j++)
{
if (isValidMove(boardArr, i, j))
{
boardArr[i, j] = 1;
ShouldPrintBoard(boardArr);
PermuteBoard(boardArr, i + 1, j + 1);
boardArr[i, j] = 0;
}

}
}
}
static void Main(string[] args)
{
int [,]boardArr = new int[SIZE.size.GetHashCode(),SIZE.size.GetHashCode()];
for(int i = 0 ; i < SIZE.size.GetHashCode() ; i++)
for(int j = 0 ; j < SIZE.size.GetHashCode() ; j++)
boardArr[i,j] = 0;
PermuteBoard(boardArr, 0, 0);

Console.WriteLine("Total Solutions {0}", count);
Console.WriteLine("Function Calls {0}", FunctionCalls);