Leetcode 74 Search a 2D Matrix

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

Integers in each row are sorted from left to right.

The first integer of each row is greater than the last integer of the previous row.

For example,

Consider the following matrix:

[
[1,   3,  5,  7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]

Given target =

3

, return

true

.

class Solution(object):
def searchMatrix(self, matrix, target):
if not matrix:
return False
rn = 0
for i in range(len(matrix)):
if matrix[i][0] > target:
break
rn = i

for x in matrix[rn]:
if x == target:
return True
return False