Leetcode 3553. Minimum Weighted Subgraph With the Required Paths II

Given a weighted tree and many queries of three distinct nodes (src1, src2, dest), return the minimum total weight of a connected subtree that contains all three nodes — which equals half the sum of their three pairwise distances. Precompute distances (e.g., via root-based distances + LCA) to answer each query in O(1).