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Lca

LeetCode 2509: Cycle Length Queries in a Tree

2026-09-11·2 mins

LeetCode Hard Tree Binary-Tree Lca

LeetCode 2509 note: in heap numbering the parent is v // 2, so climb the larger node until both meet at the LCA

LeetCode 865: Smallest Subtree with all the Deepest Nodes

2026-01-09·2 mins

LeetCode Medium Tree Binary-Tree Bfs Dfs Lca

LeetCode 865 note: BFS to the last level and climb together, or one DFS returning (depth, node)