Leetcode解题-Search a 2D Matrix

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描述

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.

分析

就是二分查找，多一个坐标转换。

代码

Python

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class Solution(object):
    def searchMatrix(self, matrix, target):
        """
        :type matrix: List[List[int]]
        :type target: int
        :rtype: bool
        """
        m = len(matrix)
        if m == 0:
            return False
        n = len(matrix[0])
        low = 0
        high = m * n - 1
        while low <= high:
            mid = low + (high - low) / 2
            x, y = divmod(mid, n)
            if matrix[x][y] == target:
                return True
            elif matrix[x][y] > target:
                high = mid - 1
            else:
                low = mid + 1
        return False

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