Horizontal distance(hd) of root = 0
    If you go left then hd = hd(of its parent)-1, and
    if you go right then hd = hd(of its parent)+1.

1
        /
       2    3
      /   /
     4   5 6  7

             8

Ok so for the first example,
    Horizontal distance of node with value 1: 0, level = 1
    Horizontal distance of node with value 2: 0 - 1 = -1, level = 2
    Horizontal distance of node with value 3: 0 + 1 = 1, level = 2
    Horizontal distance of node with value 4: -1 - 1 = -2, level = 3
    Horizontal distance of node with value 5: -1 + 1 = 0, level = 3
    Horizontal distance of node with value 6: 1 - 1 = 0, level = 3
    Horizontal distance of node with value 7: 1 + 1 = 2, level = 3
    Horizontal distance of node with value 8: 0 + 1 = 1, level = 4

    So for each vertical line that is for hd=0, print those nodes which appear in the last level of that line.
    So for hd = -2, print 4
    for hd = -1, print 2
    for hd = 0, print 5 and 6 because they both appear in the last level of that vertical line
    for hd = 1, print 8
    for hd = 2, print 7

1
      /
    2         3
   /        /
  4   5     6     7
 /  /    /     /
8  9 10 11 12 13 14 15

Similarly for this example
hd of node with value 1: 0, , level = 1
hd of node with value 2: -1, level = 2
hd of node with value 3: 1, level = 2
hd of node with value 4: -2, level = 3
hd of node with value 5: 0, , level = 3
hd of node with value 6: 0, level = 3
hd of node with value 7: 2, level = 3
hd of node with value 8: -3, level = 4
hd of node with value 9: -1, level = 4
hd of node with value 10: -1, level = 4
hd of node with value 11: 1, level = 4
hd of node with value 12: -1, level = 4
hd of node with value 13: 1, level = 4
hd of node with value 14: 1, level = 4
hd of node with value 15: 3, level = 4

So, the output will be:
hd = -3, print 8
hd = -2, print 4
hd = -1, print 9 10 12
hd = 0, print 5 6
hd = 1, print 11 13 14
hd = 2, print 7
hd = 3, print 15

So the ouput will be:
8 4 9 10 12 5 6 11 13 14 7 15

void printBottom(Node *node, int level, int hd, int min, map< int, vector<int> >& visited, int lev[], int l)
{
     if(node == NULL)
             return;
     if(level == 1){
              if(lev[hd-min] == 0 || lev[hd-min] == l){
                      lev[hd-min] = l;
                      visited[hd-min].push_back(node->data);
              }
     }
     else if(level > 1)
     {
          printBottom(node->left, level-1, hd-1, min, visited, lev, l);
          printBottom(node->right, level-1, hd+1, min, visited, lev, l);
     }
}


int main()
{
    find the minimum and maximum values for hd via DFS

    int lev[max-min+1]; //lev[hd] contains the maximum level for which we have found nodes with this value of hd; initialized with 0's

    map < int, vector<int> > visited; //the nodes in the bottom view

    int h = height(root);

    for (int i=h; i>0; i--){
        printBottom(root, i, 0, min, visited, lev, i);
    }

    output visited
}

void printBottom(Node *node, int level, int hd, int min, map< int, vector<int> >& visited, int lev[])
{
     if(node == NULL)
             return;
     if(lev[hd-min] < level){
         lev[hd-min] = level;
         visited[hd-min] = new vector<int>; //erase old values, they are hidden by the current node
     }
     if(lev[hd-min] <= level){
         visited[hd-min].push_back(node->data);
     }
     printBottom(node->left, level+1, hd-1, min, visited, lev);
     printBottom(node->right, level+1, hd+1, min, visited, lev);
}

void fillLev(Node *node, int level, int hd, int min, int lev[])
{
     if(node == NULL)
             return;
     if(lev[hd-min] < level){
         lev[hd-min] = level;
     }
     fillLev(node->left, level+1, hd-1, min, lev);
     fillLev(node->right, level+1, hd+1, min, lev);
}
void printBottom(Node *node, int level, int hd, int min, int lev[])
{
     if(node == NULL)
             return;
     if(lev[hd-min] == level){
         cout << node->data;
     }
     printBottom(node->left, level+1, hd-1, min, lev);
     printBottom(node->right, level+1, hd+1, min, lev);
}

public class node
        {
            public int data;
            public node left, right;
            public int hd;
        };

        // A utility function to create a new
        // Binary Tree node
        static node newNode(int item)
        {
            node temp = new node();
            temp.data = item;
            temp.left = null;
            temp.right = null;
            return temp;
        }

static void rightViewOfBT(node root)
        {
            Queue<node> queue = new Queue<node>();
            SortedDictionary<int, int> treeMap = new SortedDictionary<int, int>();
            int hd = 0;
            root.hd = hd;
            queue.Enqueue(root);
            while(queue.Count > 0)
            {
                node temp = queue.Peek();
                queue.Dequeue();

                if (treeMap.ContainsKey(temp.hd))
                {
                    treeMap[temp.hd] = temp.data;
                }
                else
                {
                    treeMap.Add(temp.hd, temp.data);
                }

                if (temp.left != null)
                {
                    temp.left.hd = temp.hd - 1;
                    queue.Enqueue(temp.left);
                }

                if (temp.right != null)
                {
                    temp.right.hd = temp.hd + 1;
                    queue.Enqueue(temp.right);
                }
            }
            foreach (var tree in treeMap)
                Console.Write(tree.Value);
        }

static void Main(string[] args)
        {
            node root = newNode(1);
            root.left = newNode(2);
            root.right = newNode(3);
            root.left.left = newNode(4);
            root.left.right = newNode(5);
            root.left.left.right = newNode(8);
            root.left.right.left = newNode(9);
            root.right.left = newNode(6);
            root.right.right = newNode(7);
            root.right.right.right = newNode(11);
            root.right.left.right = newNode(10);
            rightViewOfBT(root);
        }