old_contents: # Time:  O(logm + logn)
  # Space: O(1)
  #
  # 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 searchMatrix(self, matrix, target):
          """
          :type matrix: List[List[int]]
          :type target: int
          :rtype: bool
          """
          if matrix == []:
              return False
          
          m, n = len(matrix), len(matrix[0])
          left, right = 0, m * n
          while left < right:
              mid = left + (right - left) / 2
              if matrix[mid / n][mid % n] >= target:
                  right = mid
              else:
                  left = mid + 1
  
          return left < m * n and matrix[left / n][left % n] == target
  
  
  if __name__ == "__main__":
      matrix = [[1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 50]]
      print Solution().searchMatrix(matrix, 3)
  
new_contents: # Time:  O(logm + logn)
  # Space: O(1)
  #
  # 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 searchMatrix(self, matrix, target):
          """
          :type matrix: List[List[int]]
          :type target: int
          :rtype: bool
          """
          if not matrix:
              return False
          
          m, n = len(matrix), len(matrix[0])
          left, right = 0, m * n
          while left < right:
              mid = left + (right - left) / 2
              if matrix[mid / n][mid % n] >= target:
                  right = mid
              else:
                  left = mid + 1
  
          return left < m * n and matrix[left / n][left % n] == target
  
  
  if __name__ == "__main__":
      matrix = [[1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 50]]
      print Solution().searchMatrix(matrix, 3)
  
subject: Update search-a-2d-matrix.py