1361. Validate Binary Tree Nodes

https://leetcode.com/problems/validate-binary-tree-nodes

Description

You have n binary tree nodes numbered from 0 to n - 1 where node i has two children leftChild[i] and rightChild[i], return true if and only if all the given nodes form exactly one valid binary tree.

If node i has no left child then leftChild[i] will equal -1, similarly for the right child.

Note that the nodes have no values and that we only use the node numbers in this problem.

Example 1:

**Input:** n = 4, leftChild = [1,-1,3,-1], rightChild = [2,-1,-1,-1]
**Output:** true

Example 2:

**Input:** n = 4, leftChild = [1,-1,3,-1], rightChild = [2,3,-1,-1]
**Output:** false

Example 3:

**Input:** n = 2, leftChild = [1,0], rightChild = [-1,-1]
**Output:** false

Example 4:

**Input:** n = 6, leftChild = [1,-1,-1,4,-1,-1], rightChild = [2,-1,-1,5,-1,-1]
**Output:** false

Constraints:

• 1 <= n <= 104

• leftChild.length == rightChild.length == n

• -1 <= leftChild[i], rightChild[i] <= n - 1

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