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.
Example 1:
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| Input:
matrix = [
[1, 3, 5, 7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]
target = 3
Output: true
|
Example 2:
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| Input:
matrix = [
[1, 3, 5, 7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]
target = 13
Output: false
|
Code：
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| class Solution(object):
def searchMatrix(self, matrix, target):
"""
:type matrix: List[List[int]]
:type target: int
:rtype: bool
"""
if not matrix or target is None:
return False
rows, cols = len(matrix), len(matrix[0])
low, high = 0, rows * cols - 1
while low <= high:
mid = (low + high) / 2
num = matrix[mid / cols][mid % cols]
if num == target:
return True
elif num < target:
low = mid + 1
else:
high = mid - 1
return False
|
