Leetcode 117 Populating Next Right Pointers in Each Node II

triplebee

发布于 2018-01-12 14:53:58

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发布于 2018-01-12 14:53:58

文章被收录于专栏：计算机视觉与深度学习基础计算机视觉与深度学习基础

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,

After calling your function, the tree should look like:

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

题意和116一样，只不过这里的树不保证每一个节点都有左右孩子。

找next的时候一定要找到有孩子的next才行，而且为了避免next的next没有连接的情况，应该先遍历右子树。

/**
 * Definition for binary tree with next pointer.
 * struct TreeLinkNode {
 *  int val;
 *  TreeLinkNode *left, *right, *next;
 *  TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {}
 * };
 */
class Solution {
public:
    void connect(TreeLinkNode *root) {
        if(!root) return ; 
        if(root->right)   
        {  
            TreeLinkNode *p=root;
            while(p->next)
            {
                p=p->next;
                if(p->left) 
                {
                    root->right->next=p->left;
                    break;
                }
                else if(p->right)
                {
                    root->right->next=p->right;
                    break;
                }
            }connect(root->right);  //先遍历右子树
        }
        if(root->left)   
        {  
            if(root->right) 
                root->left->next=root->right;
            else 
            {
                TreeLinkNode *p=root;
                while(p->next)
                {
                    p=p->next;
                    if(p->left) 
                    {
                        root->left->next=p->left;
                        break;
                    }
                    else if(p->right)
                    {
                        root->left->next=p->right;
                        break;
                    }
                }
            }
            connect(root->left); 
        }  
    }
};

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原始发表：2016-10-14 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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