LeetCode Online Judge 题目C# 练习 - Valid Sudoku

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.
The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

public static bool ValidSudoku(List<List<char>> board)
{
for (int i = 0; i < board.Count; i++)
{
for (int j = 0; j < board[0].Count; j++)
{
if (board[i][j] != '.')
if (!isValid(board, i, j))
return false;
}
}

public static bool isValid(List<List<char>> board, int r, int c)
{
//////////////CHECK ROW/////////////////////
bool[] Row = new bool[9];
for (int i = 0; i < 9; i++)
{
if (board[r][i] >= '1' && board[r][i] <= '9')
{
if (Row[board[r][i] - '1'] == false)
Row[board[r][i] - '1'] = true;
else
return false;
}
}

/////////////CHECK COLUMN//////////////////
bool[] Col = new bool[9];
for (int i = 0; i < 9; i++)
{
if (board[i][c] >= '1' && board[i][c] <= '9')
{
if (Col[board[i][c] - '1'] == false)
Col[board[i][c] - '1'] = true;
else
return false;
}
}

/////////////CHECK GRID///////////////////
bool[] Grid = new bool[9];
// r / 3 * 3 = beginning row number of that grid
// c / 3 * 3 = beginning column number of that grid
for (int i = (r / 3) * 3; i < (r / 3) * 3 + 3; i++)
{
for (int j = (c / 3) * 3; j < (c / 3) * 3 + 3; j++)
{
if (board[i][j] >= '1' && board[i][j] <= '9')
{
if (Grid[board[i][j] - '1'] == false)
Grid[board[i][j] - '1'] = true;
else
return false;
}
}
}

return true;
}

代码分析：

　　不就是前面一题的helper function吗?