[LeetCode] 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.

可以参见：http://www.leetcode.com/2010/10/searching-2d-sorted-matrix.html

非常精彩

 1 class Solution {
 2 public:
 3     bool searchMatrix(vector<vector<int> > &matrix, int target) {
 4         // Start typing your C/C++ solution below
 5         // DO NOT write int main() function
 6         int i = 0, j = matrix[0].size() - 1;
 7         
 8         while (i < matrix.size() && j >= 0)
 9         {
10             if (target == matrix[i][j])
11                 return true;
12             else if (target < matrix[i][j])
13                 j--;
14             else
15                 i++;
16         }
17         
18         return false;
19     }
20 };