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.

class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) 
    {
        if(matrix.size() == 0)
        {
            return false;
        }
        int i = 0;
        int j = matrix[0].size() - 1;
        while(1)
        {
            if(matrix[i][j] == target)
            {
                return true;
            }
            if(matrix[i][j] > target)
            {
                -- j;
            }else
            {
                ++ i;
            }
            if(i >= matrix.size() || j < 0)
            {
                return false;
            }
        }    
        return false;
    }
};