Search 2D matrix

Write an efficient algorithm to judge m x n Matrix , Is there a target value . The matrix has the following characteristics ：

The integers in each row are arranged in ascending order from left to right .
The first integer in each row is greater than the last integer in the previous row .

source ： Power button （LeetCode）
link ：https://leetcode.cn/problems/search-a-2d-matrix

class Solution {
    
public:
    bool searchMatrix(vector<vector<int>> &matrix, int target) {
    
            
            int row=matrix.size();
            int col=matrix[0].size();
            if(row==0||col==0)  return false;
            int l=0,r=row*col-1;
            while(l<r)
            {
    
                int mid=l+(r-l)/2;
                if(matrix[mid/col][mid%col]<target)
                {
    
                    l=mid+1;
                }
                else
                {
    
                    r=mid;
                }
            }
            return target==matrix[l/col][l%col]?true:false;
    }
};