Spiral Order Matrix I

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

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]

*/



vector<int> Solution::spiralOrder(const vector<vector<int> > &A) {
    vector<int> res;
    int row1 = 0;
    int col1 = 0;
    int row2 = A.size()-1;
    int col2 = A[0].size()-1;


    while (row1 <= row2 && col1 <= col2){
        for(int i = col1; i <= col2; ++i){
            res.push_back(A[row1][i]);
        }

        row1++;
        for(int i = row1; i <= row2; ++i){
            res.push_back(A[i][col2]);
        }
        col2--;
        if(row1 <= row2){
            for(int i = col2; i >= col1; --i){
                res.push_back(A[row2][i]);
            }
        row2--;
        }
        
        if(col1 <= col2){
            for(int i = row2; i >= row1; --i){
                res.push_back(A[i][col1]);
            }
            col1++;
        }
        
    }
    return res;
}