36. Valid Sudoku - python3

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

1. Each row must contain the digits 1-9 without repetition.
2. Each column must contain the digits 1-9 without repetition.
3. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.

Note:

• A Sudoku board (partially filled) could be valid but is not necessarily solvable.
• Only the filled cells need to be validated according to the mentioned rules.

Approach 1:

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        
        for i in range(0, len(board)):
            for j in range(0, len(board)):
                row = board[i][:j] + board[i][j+1:]
                if board[i][j] != '.':
                    if board[i][j] in row:
                        return False
        
        return True

여기서 col, box 를 정해줘서 계산하려했는데 범위 잡기가 어렵고 리스트에 값을 넣기가 별로임

루션아~~ 솔루션아~~

One iteration

Solution 1: Runtime: 96 ms - 64.81% / Memory Usage: 14.3 MB - 32.53%

class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        
        rows = [{} for i in range(9)]
        columns = [{} for i in range(9)]
        boxes = [{} for i in range(9)]
        
        for i in range(0, len(board)):
            for j in range(0, len(board)):
                num = board[i][j]
                if num != '.':
                    num = int(num)
                    box_index = (i // 3 ) * 3 + j // 3

                    # keep the current cell value
                    rows[i][num] = rows[i].get(num, 0) + 1
                    columns[j][num] = columns[j].get(num, 0) + 1
                    boxes[box_index][num] = boxes[box_index].get(num, 0) + 1

                    # check if this value has been already seen before
                    if rows[i][num] > 1 or columns[j][num] > 1 or boxes[box_index][num] > 1:
                        return False
        
        return True

rows, columns, boxed 를 9 크기의 딕셔너리로 만들어줌

num 이 '.' 이 아닐때만, num 을 int 형으로 바꿔주고
box_index 를 설정해준다

rows, columns, boxes 의 num 위치의 값을 get 해와서 +1 해줌

rows, columns, boxes 에서 num 은 오직 1개만 있어야 하므로 1을 초과하면 False

이거도 뭔가 외워야할듯..