073 Set Matrix Zeroes
这道题唯一有点tricky的地方就是 需要O(1) 的space, 这样就利用第一个行 和第一列作为整个matrix的标记位,再用 row 和 col两个作为第一列和第一个行的标志位
class Solution: # @param {integer[][]} matrix # @return {void} Do not return anything, modify matrix in-place instead. def setZeroes(self, matrix): m = len(matrix) if m == 0: return matrix n = len(matrix[0]) row, col = False, False for j in range(0 ,n): if matrix[0][j] == 0: row = True break for i in range(0,m): if matrix[i][0] == 0: col = True break for i in range(0, m): for j in range(0,n): if matrix[i][j] == 0: matrix[i][0] = 0 matrix[0][j] = 0 for i in range(1, m): for j in range(1,n): if matrix[i][0] == 0 or matrix[0][j] == 0: matrix[i][j] = 0 if row: for j in range(0 ,n): matrix[0][j] = 0 if col: for i in range(0,m): matrix[i][0] = 0