```
class Solution(object):
def searchMatrix(self, matrix, target):
"""
:type matrix: List[List[int]]
:type target: int
:rtype: bool
"""
if matrix == [] or (len(matrix) == 0 or len(matrix[0])==0): return False
n = len(matrix) - 1
m = len(matrix[0]) - 1
j = m
start = matrix[0][m]
for i in range(n+1):
if matrix[i][j] == target:
return True
elif j>=0 and matrix[i][j] > target:
while j>=0 and matrix[i][j] >= target :
if matrix[i][j] == target: return True
j -= 1
return False
```