41 leetcode - Search a 2D Matrix II

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本文介绍了一种高效的算法，用于在一个特殊排列的二维矩阵中查找特定数值。该矩阵每一行从左到右递增排序，每一列从上到下递增排序。通过从矩阵右上角开始比较并逐步调整搜索方向，可以快速定位目标值。

#!/usr/bin/python
# -*- coding: utf-8 -*-
'''
Search a 2D Matrix II
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 in ascending from left to right.
Integers in each column are sorted in ascending from top to bottom.
For example,
Consider the following 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]
]
Given target = 5, return true.
Given target = 20, return false.
'''
class Solution(object):
    def searchMatrix(self, matrix, target):
        """
        :type matrix: List[List[int]]
        :type target: int
        :rtype: bool
        """
        if not matrix:
            return False
        row_length,col_length = len(matrix),len(matrix[0])
        row = row_length - 1
        col = 0

        while row >= 0 and col < col_length:
            if matrix[row][col] == target:
                return True
            elif matrix[row][col] > target:
                row -= 1
            else:
                col += 1

        return False



if __name__ == "__main__":
    s = Solution()
    b = [[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]]
    print s.searchMatrix(b,63)