leetcode240 Search a 2D Matrix II

 1 """
 2 Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
 3     Integers in each row are sorted in ascending from left to right.
 4     Integers in each column are sorted in ascending from top to bottom.
 5 Example:
 6 Consider the following matrix:
 7 [
 8   [1,   4,  7, 11, 15],
 9   [2,   5,  8, 12, 19],
10   [3,   6,  9, 16, 22],
11   [10, 13, 14, 17, 24],
12   [18, 21, 23, 26, 30]
13 ]
14 Given target = 5, return true.
15 Given target = 20, return false.
16 """
17 """
18 剑指offer原题，很经典的一道题
19 AC
20 """
21 class Solution:
22     def searchMatrix(self, matrix, target):
23         """
24         :type matrix: List[List[int]]
25         :type target: int
26         :rtype: bool
27         """
28         if not matrix:
29             return False
30         m = len(matrix)
31         n = len(matrix[0])
32         i, j = m-1, 0
33         while i >= 0 and j < n:
34             if target > matrix[i][j]:
35                 j += 1
36             elif target < matrix[i][j]:
37                 i -= 1
38             else:
39                 return True
40         return False