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Clarifying Questions:

  1. Input Details:
    • What is the structure of the tree? (Assuming it’s a binary tree)
    • What are the given values for the new row depth d and the integer value v for the nodes to be added?
  2. Constraints:
    • How large can the tree be? (The number of nodes)
    • What should be done if d is 1?

Code:

Here’s a Python solution for the problem:

# Definition for a binary tree node.
class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def addOneRow(root: TreeNode, v: int, d: int) -> TreeNode:
    if d == 1:
        new_root = TreeNode(v)
        new_root.left = root
        return new_root
    
    def dfs(node, depth):
        if not node:
            return
        
        if depth == d - 1:
            old_left = node.left
            old_right = node.right
            node.left = TreeNode(v)
            node.right = TreeNode(v)
            node.left.left = old_left
            node.right.right = old_right
        else:
            dfs(node.left, depth + 1)
            dfs(node.right, depth + 1)
    
    dfs(root, 1)
    return root

Strategy:

  1. Handle the Special Case for Depth 1:
    • If the depth d is 1, we create a new root node with value v, and the old tree becomes the left subtree of this new node.
  2. Depth-First Search (DFS) for General Case:
    • Use DFS to traverse the tree.
    • Traverse the tree to the level just above the target level d.
    • At each node at depth d-1, add new nodes with value v as the left and right children.
    • Connect the original left and right subtrees to the new nodes accordingly.

Time Complexity:

If you have any questions or need further clarifications or modifications in the code, please let me know!

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