74. Search a 2D Matrix java solutions

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.

 1 public class Solution {
 2     public boolean searchMatrix(int[][] matrix, int target) {
 3         int m = matrix.length, n = matrix[0].length;
 4         if(m == 0 || n == 0) return false;
 5         int i = m-1,j = 0;
 6         while(i >= 0 && j < n){
 7             if(matrix[i][j] == target) return true;
 8             if(matrix[i][j] > target) i--;
 9             else j++;
10         }
11         return false;
12     }
13 }

该题矩阵也是有特点的。对比题目：

http://www.cnblogs.com/guoguolan/p/5620209.html

解法二：可以使用二分查找做，不过应该没有利用矩阵的特点来做速度快。