LeetCode——Populating Next Right Pointers in Each Node

Populating Next Right Pointers in Each Node

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

Java代码：

/**
* 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) {
if(root == null) return;
if(root.left == null)return;
root.left.next = root.right;

connect(root.left);
connect(root.right);
TreeLinkNode tmp_1 = new TreeLinkNode(0);
TreeLinkNode tmp_2 = new TreeLinkNode(0);
if(root.left.left == null) return;
tmp_1 = root.left.right;
tmp_2 = root.right.left;
while(tmp_1 != null)
{
tmp_1.next = tmp_2;
tmp_1 = tmp_1.right;
tmp_2 = tmp_2.left;
}
return;
}
}