leetcode Spiral Matrix I

class Solution {
public:
vector<int> spiralOrder(vector<vector<int> > &matrix)
{
vector<int>v;
int m=matrix.size();
if(m==0)return v;
int n=matrix[0].size();
for(int i=0;2*i+1<=m&&2*i+1<=n;i++)
{
for(int k=i;k<n-i;k++)
{
v.push_back(matrix[i][k]);
}
for(int k=i+1;k<m-i-1;k++)
{
v.push_back(matrix[k][n-i-1]);
}
if(m-1-i>=i+1)
{
for(int k=n-1-i;k>=i;k--)
{
v.push_back(matrix[m-1-i][k]);
}
}
if(n-1-i>=i+1)
{
for(int k=m-2-i;k>=i+1;k--)
{
v.push_back(matrix[k][i]);
}
}
}
return v;
}
};