p162.java

// https://practice.geeksforgeeks.org/problems/right-view-of-binary-tree/1

/*Given a Binary Tree, find Right view of it. Right view of a Binary Tree is set of nodes visible when tree is viewed from right side.

Right view of following tree is 1 3 7 8.

          1
       /     \
     2        3
   /   \      /    \
  4     5   6    7
    \
     8

Example 1:

Input:
       1
    /    \
   3      2
Output: 1 2
Example 2:

Input:
     10
    /   \
  20     30
 /   \
40  60 
Output: 10 30 60
Your Task:
Just complete the function rightView() that takes node as parameter and returns the right view as a list. 

Expected Time Complexity: O(N).
Expected Auxiliary Space: O(Height of the Tree).

Constraints:
1 ≤ Number of nodes ≤ 105
0 ≤ Data of a node ≤ 105*/

/*Complete The Function Provided
Given Below is The Node Of Tree
class Node
{
    int data;
    Node left, right;
    public Node(int data)
    {
        this.data = data;
         left = right = null;
    }
}*/


class Solution{
    ArrayList<Integer> rightView(Node node) {
    ArrayList<Integer> ls=new ArrayList<>();
    rightRecur(node,0,ls);
    return ls;
    }
    public static void rightRecur(Node node,int level,List<Integer> ls){
        if(node==null){
            return;
        }
        if(ls.size()==level){
            ls.add(node.data);
        }
        rightRecur(node.right,level+1,ls);
        rightRecur(node.left,level+1,ls);
    }
}