116. Populating Next Right Pointers in Each Node LeetCode Solution

In this guide, you will get 116. Populating Next Right Pointers in Each Node LeetCode Solution with the best time and space complexity. The solution to Populating Next Right Pointers in Each Node problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Populating Next Right Pointers in Each Node solution in C++
Populating Next Right Pointers in Each Node solution in Java
Populating Next Right Pointers in Each Node solution in Python
Additional Resources

116. Populating Next Right Pointers in Each Node LeetCode Solution image

Problem Statement of Populating Next Right Pointers in Each Node

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:

struct Node {
int val;
Node *left;
Node *right;
Node *next;
}

Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.
Initially, all next pointers are set to NULL.

Example 1:

Input: root = [1,2,3,4,5,6,7]
Output: [1,#,2,3,#,4,5,6,7,#]
Explanation: Given the above perfect binary tree (Figure A), your function should populate each next pointer to point to its next right node, just like in Figure B. The serialized output is in level order as connected by the next pointers, with ‘#’ signifying the end of each level.

Example 2:

Input: root = []
Output: []

Constraints:

The number of nodes in the tree is in the range [0, 212 – 1].
-1000 <= Node.val <= 1000

Follow-up:

You may only use constant extra space.
The recursive approach is fine. You may assume implicit stack space does not count as extra space for this problem.

Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(h)

116. Populating Next Right Pointers in Each Node LeetCode Solution in C++

class Solution {
 public:
  Node* connect(Node* root) {
    if (root == nullptr)
      return nullptr;
    connectTwoNodes(root->left, root->right);
    return root;
  }

 private:
  void connectTwoNodes(Node* p, Node* q) {
    if (p == nullptr)
      return;
    p->next = q;
    connectTwoNodes(p->left, p->right);
    connectTwoNodes(q->left, q->right);
    connectTwoNodes(p->right, q->left);
  }
};
/* code provided by PROGIEZ */

116. Populating Next Right Pointers in Each Node LeetCode Solution in Java

class Solution {
  public Node connect(Node root) {
    if (root == null)
      return null;
    connectTwoNodes(root.left, root.right);
    return root;
  }

  private void connectTwoNodes(Node p, Node q) {
    if (p == null)
      return;
    p.next = q;
    connectTwoNodes(p.left, p.right);
    connectTwoNodes(q.left, q.right);
    connectTwoNodes(p.right, q.left);
  }
}
// code provided by PROGIEZ

116. Populating Next Right Pointers in Each Node LeetCode Solution in Python

class Solution:
  def connect(self, root: 'Node | None') -> 'Node | None':
    if not root:
      return None

    def connectTwoNodes(p, q) -> None:
      if not p:
        return
      p.next = q
      connectTwoNodes(p.left, p.right)
      connectTwoNodes(q.left, q.right)
      connectTwoNodes(p.right, q.left)

    connectTwoNodes(root.left, root.right)
    return root
 # code by PROGIEZ