Search a 2D Matrix，search2dmatrix

Search a 2D Matrix，search2dmatrix

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 class Solution {
 2 public:
 3     bool searchMatrix(vector<vector<int>>& matrix, int target) {
 4         if(matrix.size() == 0){
 5             return false;
 6         }
 7         if(matrix[0].size() == 0){
 8             return false;
 9         }
10         
11         int rowNumber = 0;
12         int colNumber = matrix[0].size()-1;
13         
14         while(rowNumber < matrix.size() && colNumber >= 0){
15             
16             if(matrix[rowNumber][colNumber] > target){
17                 colNumber--;
18             }else if(matrix[rowNumber][colNumber] < target){
19                 rowNumber++;
20             }else{
21                 return true;
22             }
23         }
24         return false;
25     }
26 };