Medium · Trees

Populate next pointers to right

Given the root of a perfect binary tree (every internal node has two children and all leaves are on the same level), set each node's next pointer to the node immediately to its right on the same level, or to null for the last node of each level, and return the root.

{
  "tree": [1, 2, 3, 4, 5, 6, 7]
}

{
  "tree": [1, 2, 3]
}