Valid Sudoku

【问题描述】

Determine if a Sudoku is valid, according to: .

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

Note:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

【解决方案】

bool isValidSudoku(char** board, int boardRowSize, int boardColSize) {
    bool flag[9] = { 0 };
    int i, j;

    /* rows */
    for (i = 0; i < boardRowSize; i++)
    {
        for (j = 0; j < boardColSize; j++)
        {
            if (board[i][j] != '.')
            {
                int n = board[i][j] - '1'; /* digits start with 1 */
                if (flag[n]) return false;
                else flag[n] = true;
            }
        }
        memset(flag, 0, sizeof(flag));
    }

    /* columns */
    for (j = 0; j < boardColSize; j++)
    {
        for (i = 0; i < boardRowSize; i++)
        {
            if (board[i][j] != '.')
            {
                int n = board[i][j] - '1';
                if (flag[n]) return false;
                else flag[n] = true;
            }
        }
        memset(flag, 0, sizeof(flag));
    }

    /* boxes */
    int ii, jj;
    for (ii = 0; ii < boardRowSize; ii += 3)
    {
        for (jj = 0; jj < boardColSize; jj += 3)
        {
            for (i = 0; i < 3; i++)
            {
                for (j = 0; j < 3; j++)
                {
                    if (board[i + ii][j + jj] != '.')
                    {
                        int n = board[i + ii][j + jj] - '1';
                        if (flag[n]) return false;
                        flag[n] = true;
                    }
                }
            }
            memset(flag, 0, sizeof(flag));
        }
    }
    return true;
}