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.

Solution:

class Solution {public:    bool searchMatrix(vector<vector<int> > &matrix, int target) {        int m = matrix.size();        int n = matrix[0].size();        int left = 0, right = m - 1;        while(left <= right)        {            int mid = (left + right) / 2;            if(target == matrix[mid][0]) return true;            else if(target > matrix[mid][0]) left = mid + 1;            else right = mid - 1;        }        int row = max(right, 0);        left = 0;        right = n - 1;        while(left <= right)        {            int mid = (left + right) / 2;            if(target == matrix[row][mid]) return true;            else if(target > matrix[row][mid]) left = mid + 1;            else right = mid - 1;        }                return false;    }};