Populating Next Right Pointers In Each Node II Problem


Description

LeetCode Problem 117.

Given a binary tree

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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:

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Input: root = [1,2,3,4,5,null,7]
Output: [1,#,2,3,#,4,5,7,#]
Explanation: Given the above 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:

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Input: root = []
Output: []

Constraints:

  • The number of nodes in the tree is in the range [0, 6000].
  • -100 <= Node.val <= 100


Sample C++ Code

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class Solution {
public:
    Node* connect(Node* root) {
        Node* curr = root;
        Node* head = new Node;
        Node* level;
        while (curr != NULL) {
            level = head;
            while (curr != NULL) {
                if (curr->left != NULL) {
                    level->next = curr->left;
                    level = level->next;
                }
                if (curr->right != NULL) {
                    level->next = curr->right;
                    level = level->next;
                }
                curr = curr->next;
            }
            curr = head->next;
            head->next = NULL;
        }
        return root;
    }
};




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