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  1. Practice
  2. Data Structures
  3. Trees
  4. Tree : Top View
  5. Discussions

Tree : Top View

  • peterkirby + 5 comments

    Simple version.

    void top_view(node* root, int order = 0) {
    if (root == NULL) return;
    if (order <= 0) top_view(root->left, -1);
    cout << root->data << " ";
    if (order >= 0) top_view(root->right, 1);
}
    • LenaElika + 11 comments

      I came up with a similar solution in Java :) So far, I like it the most.

      void top_view(Node root)
{
    top_view(root, 0);
}

void top_view(Node root, int side)
{
    if (root != null) {
        if (side <= 0) {
            top_view(root.left, -1);
        }
        
        System.out.print(root.data + " ");
        
        if (side >= 0) {
            top_view(root.right, 1);
        }
    }
}
      • vuleenguyen_92 + 0 comments

        Your are very good!! Perfect Solution

      • entropyjx + 0 comments

        Wow ... that is such a genius, elegant, fast, space efficient algorithm.

        And I was failing in trying to adapt a top-view algorithm with a queue helper.

      • shashi85 + 0 comments
        [deleted]
      • shashi85 + 0 comments
        [deleted]
      • shashi85 + 0 comments
        [deleted]
      • heisenberg_ab + 0 comments

        Woah, the simplest and best solution to this problem! I didnt think of this that way...

      • gonsalespalazio + 0 comments

        Very clever. :) Thank you.

      • ambitious_girl + 0 comments

        What's the logic you used in order to develop it? Thank you!

      • davidwihl + 2 comments

        I independently came up with a similar solution for Python:

        def topView(root,side=0):
    if root is None:
        return 0
    if side == 0 or side == -1:
        topView(root.left,side=-1)
    print root.data,
    if side == 0 or side == +1:
        topView(root.right,side=+1)
    return
        • HHWWHH + 0 comments
          [deleted]
        • jae_duk_seo + 0 comments

          this solution is amazing and graceful

      • aalapmaru41 + 0 comments

        Can someone please explain this code? Thank you

      • AquisBlue + 0 comments

        passes only one testcase

    • rajatbarman + 0 comments

      The most clever solution I found here :)

    • Shivan111 + 1 comment

      I dont think your solution would work if node 6(sample input) had a child in the left or right. Your solution would just skip 6 altogether and print 7 only.

      • peterkirby + 1 comment

        That describes a different problem (or different constraints). The other solutions posted here and the editorial can help clarify what is wanted.

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

    • rupav + 0 comments

      Thanks, theses conditions made my submission correct(and i know why)... i used unordered_map to do the same.

    • rajesh_kashyap60 + 0 comments

      oh my god! how did u think ?