54. Spiral Matrix

Given an m x n matrix, return all elements of the matrix in spiral order.

In this question, we will use four indices startrow=0, startcol=0, endrow=n-1, and endcol=m-1.

 vector<int> spiralOrder(vector<vector<int>>& matrix) 
    {
        vector<int> res;

        int n = matrix.size();
        int m = matrix[0].size();

        int row1 = 0;
        int row2 = n-1;

        int col1 = 0;
        int col2 = m-1;

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

            for(int j=row1+1;j<=row2;j++)
            {
                res.push_back(matrix[j][col2]);
            }

            for(int j=col2-1;j>=col1;j--)
            {
                if(row1==row2)
                {
                    break;
                }

                res.push_back(matrix[row2][j]);
            }

            for(int j=row2-1;j>=row1+1;j--)
            {
                if(col1==col2)
                {
                    break; 
                }

                res.push_back(matrix[j][col1]);
            }

            row1++;
            col1++;
            row2--;
            col2--;

        }

        return res;

    }