class Solution(object):

    def setZeroes(self, matrix):

        """

        :type matrix: List[List[int]]

        :rtype: None Do not return anything, modify matrix in-place instead.

        """

        rows = set()

        cols = set()

        count_row = len(matrix)

        count_col = len(matrix[0])

        for i in range(count_row):

            for j in range(count_col):

                if matrix[i][j] == 0:

                    rows.add(i)

                    cols.add(j)

        #for row in rows:

        #    matrix[row] = [0]*count_col

        #for col in cols:

        #    for line in matrix:

        #        line[col] = 0

        for i in rows:

            for j in xrange(count_col):

                matrix[i][j] = 0

        for i in xrange(count_row):

            for j in cols:

                matrix[i][j] = 0

        return matrix

class Solution(object):

    def setZeroes(self, matrix):

        """

        :type matrix: List[List[int]]

        :rtype: None Do not return anything, modify matrix in-place instead.

        """

        first_row = False

        first_col = False

        m = len(matrix)

        n = len(matrix[0]) #[[]]

        if m == 0 or n == 0 :

            return

        flag = -1

        for i in range(m):

            if matrix[i][0] == 0: #说明第一列本来最后就应该都等于0，以免被覆盖

                first_col = True

        for j in range(n):

            if matrix[0][j] == 0:

                first_row = True

        for i in range(1,m):

            for j in range(1,n):

                if matrix[i][j] == 0:

                    matrix[i][0] = matrix[0][j] = 0

        #第一行所有列,第一列所有行 为对照表，所以节省了空间

        for i in range(1,m):

            for j in range(1,n):

                if matrix[0][j] == 0 or matrix[i][0] == 0:

                    matrix[i][j] = 0

        if first_row:

            for j in range(n):

                matrix[0][j] = 0

        if first_col:

            for i in range(m):

                matrix[i][0] = 0