https://github.com/emahtab/binary-tree-top-view

Binary Tree Top View
https://github.com/emahtab/binary-tree-top-view

binary-tree hackerrank top-view-binary-tree

Last synced: 10 days ago
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Binary Tree Top View

• Host: GitHub
• URL: https://github.com/emahtab/binary-tree-top-view
• Owner: eMahtab
• Created: 2024-10-31T02:07:27.000Z (3 months ago)
• Default Branch: main
• Last Pushed: 2024-10-31T02:13:10.000Z (3 months ago)
• Last Synced: 2024-12-07T03:12:20.356Z (2 months ago)
• Topics: binary-tree, hackerrank, top-view-binary-tree
• Homepage:
• Size: 2.93 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Binary Tree Top View

### https://www.hackerrank.com/challenges/tree-top-view/problem

Given a pointer to the root of a binary tree, print the top view of the binary tree.

The tree as seen from the top the nodes, is called the top view of the tree.

```

For example :

   1

    \

     2

      \

       5

      /  \

     3    6

      \

       4

```

Top View : 1, 2, 5, 6

Complete the function  and print the resulting values on a single line separated by space.

## Implementation :

```java

class Solution {

	/* 

    

    class Node 

    	int data;

    	Node left;

    	Node right;

	*/

    class TreeNode {

        Node node;

        int col;

        TreeNode(Node node, int col){

            this.node = node;

            this.col = col;

        }

    }

   public static void topView(Node root) {

      Map map = new HashMap<>();

      Queue queue = new LinkedList<>();

      int leftmostCol = Integer.MAX_VALUE;

      int rightmostCol = Integer.MIN_VALUE;

      queue.add(new TreeNode(root, 0));

      while(!queue.isEmpty()) {

          int size = queue.size();

          for(int i = 1; i <= size; i++) {

              TreeNode treeNode = queue.remove();

              int column = treeNode.col;

              leftmostCol = Math.min(leftmostCol, column);

              rightmostCol = Math.max(rightmostCol, column);

              map.putIfAbsent(column, treeNode.node);

              if(treeNode.node.left != null)

                  queue.add(new TreeNode(treeNode.node.left, column -1 ));

              if(treeNode.node.right != null)

                  queue.add(new TreeNode(treeNode.node.right, column +1));    

          }

      }

      for(int column = leftmostCol; column <= rightmostCol; column++) {

          System.out.print(map.get(column).data + " ");

      }

   }

}

```