spiral matrix

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

vector<int> spiralOrder(vector<vector<int> > &matrix) {
    int row = matrix.size();
    if(row == 0) return vector<int>();
    int column = matrix[0].size();
    
    vector<int>res;
    
    int ux=0, uy=0, dx=row-1, dy=column-1;//设置4个变量
    
    while(ux < dx && uy < dy){//在同一行的话直接解决就好
        for(int i=uy; i<dy; i++){
            res.push_back(matrix[ux][i]);
        }
        
        for(int i=ux; i<dx; i++){
            res.push_back(matrix[i][dy]);
        }
        
        for(int i=dy; i>uy; i--){
            res.push_back(matrix[dx][i]);
        }
        
        for(int i=dx; i>ux; i--){
            res.push_back(matrix[i][uy]);
        }
        
        uy++; dy--;
        ux++; dx--;
    }
    
    //要用if,else if如果n==m时，ux==dx && uy == dy同时成立
    if(ux == dx){
        for(int i=uy; i<=dy; i++) res.push_back(matrix[ux][i]);
    }
    else if(uy == dy){
        for(int i=ux; i<=dx; i++) res.push_back(matrix[i][ux]);
    }
    
    return res;
    
}