Add One Row to Tree

Given the root of a binary tree and two integers val and depth, add a row of nodes with value val at the given depth depth.

Note that the root node is at depth 1.

The adding rule is:

  • Given the integer depth, for each not null tree node cur at the depth depth - 1, create two tree nodes with value val as cur's left subtree root and right subtree root.
  • cur's original left subtree should be the left subtree of the new left subtree root.
  • cur's original right subtree should be the right subtree of the new right subtree root.
  • If depth == 1 that means there is no depth depth - 1 at all, then create a tree node with value val as the new root of the whole original tree, and the original tree is the new root's left subtree.
Example 1
      4                   4
     / \                 / \
    2   6       ->      1   1
   / \ /               /     \
  3   1 5             2       6
                     / \     /
                    3   1   5
Inputroot = [4,2,6,3,1,5], val = 1, depth = 2
Output[4,1,1,2,null,null,6,3,1,5]
At depth 2, new nodes with value 1 are inserted between the root 4 and its original children 2 and 6.
Example 2
        4                         4
       /                         /
      2             ->          2
     / \                       / \
    3   1                     1   1
                             /     \
                            3       1
Inputroot = [4,2,null,3,1], val = 1, depth = 3
Output[4,2,null,1,1,3,null,null,1]
At depth 3, new nodes with value 1 are inserted below node 2, with the original subtrees becoming children of the new nodes.

Constraints

  • The number of nodes in the tree is in the range [1, 10^4].
  • The depth of the tree is in the range [1, 10^4].
  • -100 <= Node.val <= 100
  • -10^5 <= val <= 10^5
  • 1 <= depth <= the depth of tree + 1

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