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LeetCode OJ:Populating Next Right Pointers in Each Node II(指出每一个节点的下一个右侧节点II)

时间:2015-10-27 23:56:42      阅读:177      评论:0      收藏:0      [点我收藏+]

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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

指出每个节点的下一个右侧节点,前一篇博客的那个思路也可以继续使用,但由于这里的二叉树是任意的,所以应该用函数找到下一层的开始节点以及下一层的下一个节点,代码如下:

 1 class Solution{
 2 public:
 3     void connect(TreeLinkNode *root)
 4     {
 5         TreeLinkNode * prev, * curr, * start;        
 6         if(!root) return;
 7         while(root){
 8             start = findNextLevelStartNode(root);
 9             prev = start;
10             curr = findNextLevelNextNode(root, prev);
11             while(curr){
12                 prev->next = curr;
13                 prev = curr;
14                 curr = findNextLevelNextNode(root, curr);
15             }
16             root = start;
17         }
18     }
19 private:
20     TreeLinkNode * findNextLevelNextNode(TreeLinkNode * & node, TreeLinkNode * curr)//注意使用引用
21     {
22         if(node->left == curr && node->right)
23             return node->right;
24         else{
25             while(node->next){
26                 node = node->next;
27                 if(node->left != NULL && node->left != curr) return node->left;
28                 if(node->right != NULL && node->right != curr) return node->right;
29             }
30         }
31         return NULL;
32     }
33 
34     TreeLinkNode * findNextLevelStartNode(TreeLinkNode * node)
35     {
36         if(!node) return NULL;
37         if(node->left)
38             return node->left;
39         else return findNextLevelNextNode(node, node->left);
40     }
41 };

 

LeetCode OJ:Populating Next Right Pointers in Each Node II(指出每一个节点的下一个右侧节点II)

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原文地址:http://www.cnblogs.com/-wang-cheng/p/4915789.html

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