#865
Smallest Subtree with all the Deepest Nodes
pupil · 475 · lc medium +27 · verified · 77.5% accepted · 3,260 likes · top 89%
Description
In a binary tree, the depth of each node is defined as its shortest distance from the root.
Return the smallest subtree that contains all nodes at the maximum depth.
A node is called deepest if it has the greatest depth of any node in the tree.
The subtree of a node consists of that node together with all its descendants.
Example 1:
Input: root = [3,5,1,6,2,0,8,null,null,7,4]
Output: [2,7,4]
Explanation: We return the node with value 2, colored in yellow in the diagram.
The nodes coloured in blue are the deepest nodes of the tree.
Notice that nodes 5, 3 and 2 contain the deepest nodes in the tree but node 2 is the smallest subtree among them, so we return it.
Example 2:
Input: root = [1]
Output: [1]
Explanation: The root is the deepest node in the tree.
Example 3:
Input: root = [0,1,3,null,2]
Output: [2]
Explanation: The deepest node in the tree is 2, the valid subtrees are the subtrees of nodes 2, 1 and 0 but the subtree of node 2 is the smallest.
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