M-73. Set Matrix Zeroes

Set Matrix Zeroes - LeetCodeLeetCode

# 0 我的解法, O(mn), O(1), 但是lc的oj跑的太慢了...
class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        for i in range(len(matrix)):
            for j in range(len(matrix[0])):
                if matrix[i][j] == 0:
                    for a in range(len(matrix[i])):
                        matrix[i][a] = 'a' if matrix[i][a] != 0 else 0
                    for b in range(len(matrix)):
                        matrix[b][j] = 'a' if matrix[b][j] != 0 else 0
        
        for i in range(len(matrix)):
            for j in range(len(matrix[0])):
                if matrix[i][j] == 'a':
                    matrix[i][j] = 0

# 1 最简单的暴力就是新建一个矩阵, 对照新建的矩阵, 把原矩阵按操作赋0, 空间复杂度是O(nm)
# 略

# 2 稍微改进一下就是, 创建两个list, 存矩阵有0的行号和列号, 然后赋0, 空间复杂度是O(n+m)
class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        len_row = len(matrix)
        len_column = len(matrix[0])

        set_row = []
        set_column = []

        for i_row, row in enumerate(matrix):
            for i_column, element in enumerate(row):
                if element == 0:
                    set_row.append(i_row)
                    set_column.append(i_column)
        
        for i_column in set_column:
            for i in range(len_row):
                matrix[i][i_column] = 0 

        for i_row in set_row:
            for i in range(len_column):
                matrix[i_row][i] = 0 

# 3 再改进, 把每一行是否有0的信息存在每一行的第一列, 把每一列是否有0的信息存在每一列的第一
# 行, 然后再逐个赋0,时间复杂度O(mn), 空间复杂度是O(1), 因为我们只要创建一个变量存第一行或者第一列是否有0的
# 信息即可. 

class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        col_0 = 1
        
        for i in range(len(matrix)):
            for j in range(len(matrix[0])):
                if matrix[i][j] == 0:
                    matrix[i][0] = 0
                    if j == 0:
                        col_0 = 0
                    else:
                        matrix[0][j] = 0

        for i in range(1, len(matrix)):
            if matrix[i][0] == 0:
                for j in range(1, len(matrix[0])):
                    matrix[i][j] = 0
        
        for j in range(1, len(matrix[0])):
            if matrix[0][j] == 0:
                print('j: '+str(j))
                for i in range(1, len(matrix)):
                    matrix[i][j] = 0
        
        if matrix[0][0] == 0:
            for j in range(len(matrix[i])):
                matrix[0][j] = 0
        
        if col_0 == 0:
            for i in range(len(matrix)):
                matrix[i][0] = 0