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

Tree : Top View

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967 Discussions

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  • chyihuey17
     + 1 comment

    Agree the problem explanation is bad, had to google it. Basically we can think of it as root is at 0 on the x axis then the left child is at -1 and right child is at 1. If a node is at the same place on the x axis and there is another node higher up the tree/ closer to the root, it is blocked.

  • hackerrank4290
     + 0 comments

    This problem is simply not well defined. "the set of nodes visible when the tree is viewed from the top" is meaningless. There is no "top" though I suppose they mean "root". Similarly "viewed" simply does not mean anything in this context.

  • pedroramoscunha1
     + 0 comments

    Hi, I'm having an issue to run the code i did in this exercise. I tested on my machine and it worked as expected. But for some reason, the test here does not output any value. Am I doing something wrong?

    def topView(root):
    left_wing = ''
    right_wing = ''
    if(root.left is not None):
        left_wing = topView(root.left)
    if(root.right is not None):
        right_wing = topView(root.right)
        
    ''' return value if is a leaf '''
    if((root.left is None) & (root.right is None)):
        return str(root.info)
    ''' If it has only the right side '''
    if(left_wing == ''):
        return str(root.info) +' '+ right_wing
    ''' If it has only the left side '''
    if(right_wing == ''):
        return str(root.info) +' '+ left_wing
    ''' Else then check between both wings'''
    rw_max = int((right_wing.split(' '))[-1])
    lw_max = int((left_wing.split(' '))[-1])
    
    if(rw_max>=lw_max):
        return str(root.info) +' '+ right_wing
    else:
        return str(root.info) +' '+ left_wing

  • ms_salvemini
     + 0 comments

    I try to find a better definition of top view since the one presented is terrible: the list nodes, from left to the right, that projected vertically from the top to the bottom, are NOT covered by other nodes. 

    # layer: meant as horizontal layer, integer
#    < 0 (left of the root) or > 0 (right of the root)
# depth: depth in the three from zero, always positive

def explore(node, results, layer: int = 0, depth : int = 0):
    if layer not in results:
        # if it a new layer, no matter of the current depth
        results[layer] = { 'depth': depth, 'content': node.info }
    else:
        # there was already a node on this layer
        if depth < results[layer].get('depth'):
            results[layer] = { 'depth': depth, 'content': node.info }
    
    if node.left is not None:
        explore(node.left, results, layer-1, depth+1)
       
    if node.right is not None:
        explore(node.right, results, layer+1, depth+1)
    
def topView(root):
    #Write your code here
    results = {}
    explore(root, results)

    min_index = min(results.keys())
    max_index = max(results.keys())
    for i in range(min_index, max_index+1):
        print(results[i].get('content'), end=" ")

  • berkeragir
     + 0 comments

    The definition of top view is not clear at all. There should be at least two examples with expected output to help understand a better description.