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:
Example:
Given the following binary tree,
1 / 2 3 / \ 4 5 7
After calling your function, the tree should look like:
1 -> NULL / 2 -> 3 -> NULL / \ 4-> 5 -> 7 -> NULL
Approach #1: Java.
/**
* Definition for binary tree with next pointer.
* public class TreeLinkNode {
* int val;
* TreeLinkNode left, right, next;
* TreeLinkNode(int x) { val = x; }
* }
*/
public class Solution {
public void connect(TreeLinkNode root) {
TreeLinkNode dummyHead = new TreeLinkNode(0);
TreeLinkNode pre = dummyHead;
while (root != null) {
if (root.left != null) {
pre.next = root.left;
pre = pre.next;
}
if (root.right != null) {
pre.next = root.right;
pre = pre.next;
}
root = root.next;
if (root != null) {
pre = dummyHead;
root = dummyHead.next;
dummyHead.next = null;
}
}
}
}
Appraoch #2: Python.
# Definition for binary tree with next pointer.
# class TreeLinkNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
# self.next = None
class Solution:
# @param root, a tree link node
# @return nothing
def connect(self, root):
tail = dummy = TreeLinkNode(0)
while node:
tail.next = node.left
if tail.next:
tail = tail.next
tail.next = node.right
if tail.next:
tail = tail.next
node = node.next
if not node:
tail = dummy
node = dummy.next
Populating Next Right Pointers in Each Node II
原文：https://www.cnblogs.com/ruruozhenhao/p/10004493.html