I have been given a tree with n nodes and n-1 edges with it's weight. There are two people A and B. I have been given a list of nodes of size k.
A will pick a random node x from this list and B will independently pick a random node y from this list.
I have to find expected distance between these two nodes.
My way of solving it was to find the distance between all the (k*(k-1)/2)nodes of the list and dividing it by number of nodes in the list.
for ex: n=6,k=6 list=[1,2,3,4,5,6]
Node--------> 1 \(1)<-----------Weight \ 3 (3) / \(2) / \ 4 2 (4) / \ (5) / \ 5 6
My answer was coming out to be 87/6 but the actual answer was 29/6.Please help me find whatever i am doing wrong here.