40 leetcode - Search a 2D Matrix

#!/usr/bin/python# -*- coding: utf-8 -*-'''Search a 2D Matrix 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.'''class Solution(object):    def binary_search(self,l,length,target):        if not l or length == 0:            return False        left,right = 0,length - 1        while left <= right:            mid = (left + right)/2            if l[mid] == target:                return True            elif l[mid] > target:                right = mid - 1            else:                left = mid + 1        return False    def searchMatrix(self, matrix, target):        """        :type matrix: List[List[int]]        :type target: int        :rtype: bool        """        row_length,col_length = len(matrix),len(matrix[0])        if row_length == 0 or col_length == 0:            return False        index = 0        while index < row_length:            if matrix[index][0] <= target and matrix[index][col_length - 1] >= target:                return self.binary_search(matrix[index],col_length,target)            index += 1        return Falseif __name__ == "__main__":    s = Solution()    b = [[1,   3,  5,  7],[10, 11, 16, 20],[23, 30, 34, 50]]    print s.searchMatrix(b,12)