LeetCode||74. Search a 2D Matrix

最新推荐文章于 2025-05-19 23:44:29 发布

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最新推荐文章于 2025-05-19 23:44:29 发布

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本文介绍了一种高效的矩阵搜索算法，该算法能在m x n大小的矩阵中查找特定数值。矩阵特性包括每行元素从左到右递增排序及每行首元素大于前一行末元素。通过示例展示了算法的具体应用。

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.

这题类似于二分查找

不过要注意[]的情况，直接判断为FALSE

class Solution(object):
    def searchMatrix(self, matrix, target):
        """
        :type matrix: List[List[int]]
        :type target: int
        :rtype: bool
        """
        if not matrix:
            return False
        r = 0
        c = len(matrix[0]) - 1
        while r < len(matrix) and c >= 0:
            if matrix[r][c] == target:
                return True
            elif target < matrix[r][c]:
                c -= 1
            else:
                r += 1
        return False