# N Queen Problem

The N Queen, also known as eight queens puzzle, is the problem of placing N chess queens on an N×N chessboard so that no two queens attack each other.

```									```/*****Please include following header files*****/
// iostream
/***********************************************/

// std
/*****************************************/

#define N 4

static void PrintSolution(int board[N][N])
{
for (int i = 0; i < N; ++i)
{
for (int j = 0; j < N; ++j)
cout << " " << board[i][j] << " ";

cout << endl;
}
}

static bool IsSafe(int board[N][N], int row, int col)
{
int i, j;

for (i = 0; i < col; ++i)
if (board[row][i])
return false;

for (i = row, j = col; i >= 0 && j >= 0; --i, --j)
if (board[i][j])
return false;

for (i = row, j = col; j >= 0 && i < N; ++i, --j)
if (board[i][j])
return false;

return true;
}

static bool SolveNQ(int board[N][N], int col)
{
if (col >= N)
return true;

for (int i = 0; i < N; ++i)
{
if (IsSafe(board, i, col))
{
board[i][col] = 1;

if (SolveNQ(board, col + 1))
return true;

board[i][col] = 0;
}
}

return false;
}

static bool Solve()
{
int board[N][N] = {
{ 0, 0, 0, 0 },
{ 0, 0, 0, 0 },
{ 0, 0, 0, 0 },
{ 0, 0, 0, 0 }
};

if (SolveNQ(board, 0) == false)
return false;

PrintSolution(board);
return true;
}```
```

### Example

```									`bool isSolved = Solve();`
```

### Output

```									```isSolved: true

Output of Solve function:
0  0  1  0
1  0  0  0
0  0  0  1
0  1  0  0```
```