Second-best spanning tree
Given n nodes and a list of weighted undirected edges [u, v, w], return the total weight of the second-best (strictly second smallest) spanning tree: the minimum weight achievable by any spanning tree whose total weight is strictly greater than the MST weight. If every spanning tree has the same weight as the MST (or the graph is disconnected / has only one spanning tree), return -1. Edge weights are positive integers.
Implement
second_best_mst(n: int, edges: list[list[int]]) → intExamples
in
[4,[[0,1,1],[1,2,1],[2,3,1],[0,3,2],[0,2,2]]]out4What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 40 min
solution.py
InputExpectedGot
[4,[[0,1,1],[1,2,1],[2,3,1],[0,3,2],[0,2,2]]]4not run yetsample