Populating Next Right Pointers in Each Node

Populating Next Right Pointers in Each Node

 Total Accepted: 5874 Total Submissions: 17154MySubmissions Given a binary tree

struct TreeLinkNode {
TreeLinkNode *left;
TreeLinkNode *right;
TreeLinkNode *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

.Note:You may only use constant extra space.You may assume that it is a perfect binary tree (ie, all leaves are at the same level, and every parent has two children). For example,Given the following perfect binary tree,

1
/  \
2    3
/ \  / \
4  5  6  7

 After calling your function, the tree should look like:

1 -> NULL
/  \
2 -> 3 -> NULL
/ \  / \
4->5->6->7 -> NULL

preorder traversal, 也可以用BFS

public static void connect(TreeLinkNode root){if(root == null) return;if(root.left!=null) root.left.next = root.right;if(root.right!=null && root.next!=null) root.right.next= root.next.left;connect(root.left);connect(root.right);}// BFSpublic static void connect(TreeLinkNode root) {if(root == null) return;TreeLinkNode head = root;while(head!=null){TreeLinkNode subList = new TreeLinkNode(0);TreeLinkNode temp = subList;while(head!=null){if(head.left!=null) {temp.next = head.left;temp = temp.next;}if(head.right!=null) {temp.next = head.right;temp = temp.next;}head = head.next;}head = subList.next;}}