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LeetCode - Populating Next Right Pointers in Each Node II

时间:2016-01-13 17:41:17      阅读:116      评论:0      收藏:0      [点我收藏+]

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题目:

Follow up for problem "Populating Next Right Pointers in Each Node".

What if the given tree could be any binary tree? Would your previous solution still work?

Note:

  • You may only use constant extra space.

For 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

思路:

递归,对root的左右进行连接操作,然后先递归右树,再递归左树。

package tree;

public class PopulatingNextRightPointersInEachNodeII {

    public void connect(TreeLinkNode root) {
        if (root == null || (root.left == null && root.right == null)) return;

        TreeLinkNode next = root.next;
        while (next != null) {
            if(next.left != null) {
                next = next.left;
                break;
            }
            
            if (next.right != null) {
                next = next.right;
                break;
            }
            
            next = next.next;
        }
        
        if (root.right != null) 
            root.right.next = next;
         
        if (root.left != null)
            root.left.next = root.right == null ? next : root.right;
                
        connect(root.right);
        connect(root.left);
    }

}

 

LeetCode - Populating Next Right Pointers in Each Node II

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原文地址:http://www.cnblogs.com/shuaiwhu/p/5127482.html

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