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# 1123. Lowest Common Ancestor of Deepest Leaves
import leetcode
"""
given the 'root' of a binary tree, return the lowest common ancestor of its
deepest leaves. recall that the node of a binary tree is a leaf if and only
if it has no children, the depth of the root of the tree is 0. if the depth
of a node is 'd', the depth of each of its children is 'd + 1'. and the
lowest common ancestor of a set 's' is the node 'a' with the largest depth
such that every node in 's' is in the subtree with root 'a'.
"""
class Solution(object):
def lcaDeepestLeaves(self, root):
"""
:type root: Optional[TreeNode]
:rtype: Optional[TreeNode]
"""
def depth(node):
if not node:
return 0
return max(depth(node.left), depth(node.right)) + 1
def dfs(node, m, n):
if not node:
return None
if m - 1 == n:
return node
l = dfs(node.left, m, n + 1)
r = dfs(node.right, m, n + 1)
if l and r:
return node
return l if l else r
m = depth(root)
return dfs(root, m, 0)
if __name__ == "__main__":
obj = Solution()
r1 = leetcode.treenode_build(root=[3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
r2 = leetcode.treenode_build(root=[1])
r3 = leetcode.treenode_build(root=[0, 1, 3, None, 2])
print(obj.lcaDeepestLeaves(r1))
print(obj.lcaDeepestLeaves(r2))
print(obj.lcaDeepestLeaves(r3))
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