Day036 - 73. Set Matrix Zeroes

73. Set Matrix Zeroes

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0’s.

You must do it in place.

Example 1:

Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]
Output: [[1,0,1],[0,0,0],[1,0,1]]

Example 2:

Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]
Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]

Constraints:

• m == matrix.length
• n == matrix[0].length
• 1 <= m, n <= 200
• -231 <= matrix[i][j] <= 231 - 1

Follow up:

• A straightforward solution using O(mn) space is probably a bad idea.
• A simple improvement uses O(m + n) space, but still not the best solution.
• Could you devise a constant space solution?

내 풀이

class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:

        row_len = len(matrix)
        col_len = len(matrix[0])

        row_list = set()
        col_list = set()

        # matrix를 순회하며 0이 있는 row와 col을 저장
        for row_idx, row in enumerate(matrix):
            for col_idx, col in enumerate(row):
                if col == 0:
                    row_list.add(row_idx)
                    col_list.add(col_idx)


        for row in row_list:
            for col in range(col_len):
                matrix[row][col] = 0

        for col in col_list:
            for row in range(row_len):
                matrix[row][col] = 0

# Time Complexity : \(O(N)\)