動機
複習saddle back
Problem
Write an efficient algorithm that searches for a target
value in an m x n
integer matrix
. The matrix
has the following properties:
- Integers in each row are sorted in ascending from left to right.
- Integers in each column are sorted in ascending from top to bottom.
Example 1:
Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5Output: true
Example 2:
Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20Output: false
Constraints:
m == matrix.length
n == matrix[i].length
1 <= n, m <= 300
-109 <= matix[i][j] <= 109
- All the integers in each row are sorted in ascending order.
- All the integers in each column are sorted in ascending order.
-109 <= target <= 109
Sol
詳細去看saddleback-search-algorithm
class Solution:
def searchMatrix(self, ms: List[List[int]], val: int) -> bool:
a,b = len(ms)-1,0
while 0 <= a < len(ms) and 0 <= b < len(ms[a]):
if ms[a][b] == val:
return True
elif ms[a][b] < val:
b += 1
else:
a -= 1
return False