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;    }};