Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]

You should return [1,2,3,6,9,8,7,4,5].

class Solution 
{
public:
    vector<int> spiralOrder(vector<vector<int> > &matrix) 
    {
        vector<int> res;
        int n= matrix.size();
        if(n==0)
            return res;
        if(n==1)
            return matrix[0];
        int m = matrix[0].size();
        bool left_up = true;
        bool left_down = false;
        bool right_up = false;
        bool right_down = false;
        int min_i = 0;
        int max_i = n-1;
        int min_j = 0;
        int max_j = m-1;
        while(min_i<=max_i && min_j<=max_j)
        {
            if(left_up == true)
            {
                for(int j = min_j; j<=max_j; j++)
                    res.push_back(matrix[min_i][j]);
                left_up = false;
                right_up = true;
                min_i = min_i+1;
            }
            else if(right_up == true)
            {
                for(int i=min_i; i<=max_i; i++)
                    res.push_back(matrix[i][max_j]);
                max_j = max_j-1;
                right_up = false;
                right_down = true;
            }
            else if(right_down == true)
            {
                for(int j=max_j; j>=min_j; j--)
                    res.push_back(matrix[max_i][j]);
                max_i = max_i-1;
                left_down = true;
                right_down = false;
            }
            else
            {
                for(int i=max_i; i>=min_i; i--)
                    res.push_back(matrix[i][min_j]);
                min_j = min_j+1;
                left_up = true;
                left_down = false;
            }
        }
        return res;
    }
};

LeetCode--Spiral Matrix