I was trying this Problem — https://mirror.codeforces.com/contest/1004/problem/E and am getting a WA on Test-6.

My approach for solving this problem was to use —

• Binary Search — For each prospective max possible distance max_, we check how many nodes we require in our path such that the max distance from this path to other non-selected nodes is <= max_. If the number of selected nodes for the path is <= k in the problem, we mark our prospective answer as a possible and return the min out of all possible answers.

The idea seems quite simple, but I am having a hard time writing the correct implementation, especially the BFS part. Here is my submission, which WAs on Test-6 — Link

I tried reading the editorial and saw that one of the folks had a binary search approach, but I am not able to understand how did he implement the bfs part. Especially this part — All nodes of degree >= 3 should be used completely in bfs — Link to the comment | Link to the submission of the folk

Thanks :D