Search in 2D matrix -- Leetcode

Question:

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.

Answer:

class Solution {
public:
    bool searchMatrix(vector<vector<int> > &matrix, int target) {
        int m = matrix.size();
        if(m == 0)  return false;
        int n = matrix[0].size();
        if(n == 0)  return false;                              //matrix: m*n
         
        int row = 0, column = n - 1;
         
        while(row < m && column >= 0)
        {
            if(matrix[row][column] == target)
                return true;
            else if(matrix[row][column] > target)
                column--;
            else
                row++;
        }
        return false;
     }

};