73. 矩阵置零

73. 矩阵置零
class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        if not matrix or not matrix[0]:
            return
        row = len(matrix)
        col = len(matrix[0])
        matrix_ = copy.deepcopy(matrix)
        for i in range(row):
            for j in range(col):
                if matrix_[i][j]==0:
                    for k in range(row):
                        matrix[k][j]=0
                    for k in range(col):
                        matrix[i][k]=0
#如果不复制当前数组那会造成之后列和行全为0
---
#升级：如果行列中有俩个0，那么就会出现重复操作
#为简便，将其记录下，直接赋为0
class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        if not matrix or not matrix[0]:
            return
        row = len(matrix)
        col = len(matrix[0])
        row_,col_ = set(),set()
        for i in range(row):
            for j in range(col):
                if matrix[i][j]==0:
                    row_.add(i)
                    col_.add(j)
        for i in range(row):
            for j in range(col):
                if i in row_ or j in col_:
                    matrix[i][j]=0