Trees - Populating Next Right Pointers in Each Node

Given a perfect binary tree, populate each next pointer to point to the next right node. If there is no next right node, the next pointer should be set to NULL.

Input: root=[1,2,3,4,5,6,7] → each node's next points to its right neighbor

Since the tree is perfect, use constant-space level-order using existing next pointers. Process each level by linking children of connected nodes.

Iterate level by level using leftmost node of each level.
For each node at current level: node.left.next = node.right; if node.next: node.right.next = node.next.left.
Advance leftmost to leftmost.left (go to next level).

class Solution { public Node connect(Node root) { Node leftmost = root; while (leftmost != null && leftmost.left != null) { Node cur = leftmost; while (cur != null) { cur.left.next = cur.right; if (cur.next != null) cur.right.next = cur.next.left; cur = cur.next; } leftmost = leftmost.left; } return root; } }

Time Complexity: O(N)
Space Complexity: O(1)