Search 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.
	 * 
	 * */