机器人的运动范围

class Solution {
private:
    int add(int n)
    {
        int sum =0;
        while(n != 0)
        {
            sum += n%10;
            n = n/10;
        }
        return sum;
    }
    int move(int threshold, int rows, int cols, int row, int col, int& count, vector<int>&visited)
    { 
       if(row>=0 && row<rows && col>=0 && col<cols &&visited[row*cols+col]==0 && 
          add(row)+add(col)<=threshold)
       {
             visited[row*cols+col]=1;
             count++;
             move(threshold, rows, cols, row-1, col, count, visited);
             move(threshold, rows, cols, row, col+1, count, visited);
             move(threshold, rows, cols, row+1, col, count, visited);
             move(threshold, rows, cols, row, col-1, count, visited);
       }
         
        return count;
    }
public:
    int movingCount(int threshold, int rows, int cols)
    {
        vector<int> visited(rows*cols,0);
        int count = 0, col = 0, row = 0;
     //  visited[0] = 1;
        return move(threshold, rows, cols, row, col, count, visited);
    }
};