GATE 1990
February 13, 2024
Question 4365 – 2009 June UGC NET Paper 1
February 13, 2024
GATE 1990
February 13, 2024
Question 4365 – 2009 June UGC NET Paper 1
February 13, 2024

GATE 1990

Question 12

Choose the correct alternatives (More than one may be correct).

The total external path length, EPL, of a binary tree with n external nodes is, EPL = ∑wIw, where Iw is the path length of external node w),

A
≤ n2 always.
B
≥ n log2 n always.
C
Equal to n2 always.
D
O(n) for some special trees.
Question 12 Explanation: 
Here the question asked for binary tree.
It can be of 2 types:
1) Skewed tree.
2) Balanced binary tree or AVL tree.
We have to find external path length, i.e., leaf node.
We also know cost of external path = leaf node value + length of path
Now for balanced tree external path length = n × log n
But for skewed tree it will be O(n) only.
So, answer will be (D).
Correct Answer: D
Question 12 Explanation: 
Here the question asked for binary tree.
It can be of 2 types:
1) Skewed tree.
2) Balanced binary tree or AVL tree.
We have to find external path length, i.e., leaf node.
We also know cost of external path = leaf node value + length of path
Now for balanced tree external path length = n × log n
But for skewed tree it will be O(n) only.
So, answer will be (D).

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