### isValidSudoku 
from typing import *
def f_gold(board: List[List[str]]) -> bool:
    row = [[False] * 9 for _ in range(9)]
    col = [[False] * 9 for _ in range(9)]
    sub = [[False] * 9 for _ in range(9)]
    for i in range(9):
        for j in range(9):
            c = board[i][j]
            if c == '.':
                continue
            num = int(c) - 1
            k = i // 3 * 3 + j // 3
            if row[i][num] or col[j][num] or sub[k][num]:
                return False
            row[i][num] = True
            col[j][num] = True
            sub[k][num] = True
    return True