240.搜索二维矩阵II

https://leetcode.cn/problems/search-a-2d-matrix-ii/

编写一个高效的算法来搜索 *m* x *n* 矩阵 matrix 中的一个目标值 target 。该矩阵具有以下特性：

每行的元素从左到右升序排列。
每列的元素从上到下升序排列。

示例 1：

输入：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 = 5
输出：true

示例 2：

输入：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 = 20
输出：false

提示：

m == matrix.length
n == matrix[i].length
1 <= n, m <= 300
-109 <= matrix[i][j] <= 109
每行的所有元素从左到右升序排列
每列的所有元素从上到下升序排列
-109 <= target <= 109

python

from typing import List
import bisect

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        for row in matrix:
            # 在每行中使用 bisect_left 查找目标值的插入位置
            index = bisect.bisect_left(row, target)
            # 检查插入位置是否有效且等于目标值
            if index < len(row) and row[index] == target:
                return True
        return False

if __name__ == "__main__":
    sol = Solution()
    print(sol.searchMatrix([[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]], 5))  # 输出: True
    print(sol.searchMatrix([[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]], 20)) # 输出: False
    print(sol.searchMatrix([[1]], 1))  # 输出: True

参照源码实现二分，https://github.com/python/cpython/blob/main/Lib/bisect.py

python

from typing import List

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        for row in matrix:
            lo, hi = 0, len(row)
            while lo < hi:
                mid = (lo + hi) // 2
                if row[mid] < target:
                    lo = mid + 1
                else:
                    hi = mid
            # 在找到的位置检查是否是目标值
            if lo < len(row) and row[lo] == target:
                return True
        return False  # 如果未找到目标值

if __name__ == "__main__":
    sol = Solution()
    print(sol.searchMatrix([[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]], 5))  # 输出: True

240.搜索二维矩阵II ​

240.搜索二维矩阵II