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) {        int size = matrix.size();        if (size < 1)        {            return false;        }        int left = 0;        int right = size - 1;        while (left < right-1)        {            int mid = left + (right-left)/2;            if (matrix[mid][0] == target)            {                return true;            }            else if (matrix[mid][0] > target)            {                right = mid - 1;            }            else            {                left = mid;            }        }        if (matrix[left][0] == target || matrix[right][0] == target)        {            return true;        }        int row = left;        if (left != right)        {            if (matrix[right][0] < target)            {                row = right;            }        }            left = 0;        right = matrix[row].size() - 1;        while (left <= right)        {            int mid = left + (right-left)/2;            if (matrix[row][mid] == target)            {                return true;            }            else if (matrix[row][mid] > target)            {                right = mid - 1;            }            else            {                left = mid + 1;            }        }        return false;    }};