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# 2196. Create Binary Tree From Descriptions
from collections import defaultdict
"""
you are given a 2d integer array 'descriptions' where 'descriptions[i] =
[parent_i, child_i, isleft_i]' indicates that 'parent_i' is the parent of
'child_i', in a binary tree of unique values. construct the binary tree
described by 'descriptions' and return its root. the test cases will be
generated such that the binary tree is valid.
"""
# Definition for a binary tree node.
class TreeNode(object):
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution(object):
def createBinaryTree(self, descriptions):
"""
:type descriptions: List[List[int]]
:rtype: Optional[TreeNode]
"""
children = set()
m = {}
for p, c, l in descriptions:
np = m.setdefault(p, TreeNode(p))
nc = m.setdefault(c, TreeNode(c))
if l:
np.left = nc
else:
np.right = nc
children.add(c)
root = (set(m) - set(children)).pop()
return m[root]
if __name__ == "__main__":
obj = Solution()
print(
obj.createBinaryTree(
descriptions=[
[20, 15, 1],
[20, 17, 0],
[50, 20, 1],
[50, 80, 0],
[80, 19, 1],
]
)
)
print(obj.createBinaryTree(descriptions=[[1, 2, 1], [2, 3, 0], [3, 4, 1]]))
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