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In a complete $k$-ary tree, every internal node has exactly $k$ children. The number of leaves in such a tree with $n$ internal node is:

1. $nk$
2. $(n-1)k + 1$
3. $n(k-1) +1$
4. $n(k-1)$
edited | 1.4k views

Before looking at answer just  form following two equation and try to solve -->

1. Equation for total degree.
2. Equation for total node.

Answer :-> C)n(k-1) +1

Originally when we have root , there is only 1 node, which is leaf.(There is no internal node.) From that "+1" part of formula comes from this base case.

When we k children to nodes, we make root internal. So then Total Leaves = n(k-1) + 1 = (k-1) + 1 = k

In k complete k ary tree every time you add k children , you add k-1 leaves.( +k for leaves, -1 for node which you are attaching )
answered by Veteran (46.8k points)
selected
total nodes=nk+1(1 for root)

leaves =total nodes -internal nodes

=nk+1-n

=n(k-1)+1
answered by Veteran (33.3k points)
here k is not internal node ..... n is internal node and

leaves node = internal node (k-1)+1

leaves= n(k-1)+1

and total nodes = n(k-1)+1+n= nk+1

so ans should be (c)

http://www.geeksforgeeks.org/g-fact-42/

https://gateoverflow.in//1683/gate1998_2-11#viewbutton

It was typo thanks for correcting...

Option c.
answered by Loyal (3.2k points)

 leaves node = internal node (k-1)+1 leaves= n(k-1)+1 and total nodes = n(k-1)+1+n= nk+1 so ans should be (c) http://www.geeksforgeeks.org/g-fact-42/ https://gateoverflow.in//1683/gate1998_2-11#viewbutton
answered by Veteran (13.6k points)
+1 vote
#leaves * degree_of_each_leave + #internal_nodes(excluding the root) *degree_of_each_internal node + degree of root=2(number of edges)

number of leaf node is( say l)

here degree of leaf node is 1

number o internal nodes(excluding root)is n-1

degree of each internal node is k+1

degree of root is k

number of edges=l+n-1

l+(n-1)(k+1)+k=2(l+n-1)

=>l+nk-k+n-1+k=2l+2n-2

=>l=n(k-1)+1
answered by Veteran (13.6k points)
@Bhagi

more precisely just solve this two equation to get answer of any such ques!

N=ki+1

N=i+l

where  N=number of nodes i=no of internal node k= k-ary l=leaves
in some que root node is not consider as internal node but in thi que root node is consider as internal node..why ??