Leetcode Problem 865. Smallest Subtree with all the Deepest Nodes

865. Smallest Subtree with all the Deepest Nodes

Leetcode Solutions

Recursive Approach to Find Smallest Subtree Containing All Deepest Nodes

  1. Define a helper function dfs(node) that returns a tuple (max_depth, subtree) where max_depth is the maximum depth in the subtree rooted at node, and subtree is the smallest subtree containing all the deepest nodes.
  2. If node is None, return (0, None).
  3. Recursively call dfs on the left and right children of node to get their maximum depths and subtrees.
  4. Compare the maximum depths from the left and right subtrees.
  5. If they are equal, the current node is the LCA, and we return (max_depth + 1, node).
  6. If they are not equal, return the result from the child with the greater maximum depth, with the depth incremented by 1.
  7. The initial call will be dfs(root), and the second element of the returned tuple is the desired smallest subtree.
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Iterative Approach with Annotated Depth

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