Number of ways to choose 3 nodes in a graph such that all are equidistant from each other.

Note: Number of edges = Number of nodes -1

Example:

Input: [1,2] [1,3] [1,4] [1,5]

Constraints 2 < N <= 10^4

Output: 4

My approach:

1.Bfs from all nodes

2.ans += NC3 : N = number of nodes on same level.

Problem: Unable to handle case of repetition, Pls look into it and provide me a solution for the same. Ps: ive been stuck on this for a long time :(