leetcode[117]:Populating Next Right Pointers in Each Node II

最新推荐文章于 2021-09-24 12:05:40 发布

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本文介绍了一种在任意二叉树中填充每个节点的next指针的方法，使得每个节点指向其右侧相邻节点。该方法仅使用常数额外空间，并通过递归实现。文章提供了具体的C风格伪代码。

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Populating Next Right Pointers in Each Node II

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

/**
 * Definition for binary tree with next pointer.
 * struct TreeLinkNode {
 *  int val;
 *  struct TreeLinkNode *left, *right, *next;
 * };
 *
 */
void connect(struct TreeLinkNode *root) {
    int i;
    struct TreeLinkNode *tmp;
    if(!root) return;
    if(root->left)
    {
        if(root->right)
            root->left->next=root->right;
        else if(root->next)
        {
            tmp=root->next;

            while(tmp)
            {
                if(tmp->left)
                    {
                        root->left->next=tmp->left;
                        break;
                    }
                if(tmp->right)
                    {
                        root->left->next=tmp->right;
                        break;
                    }
                tmp=tmp->next;
            }
        }
    }
    if(root->right)
    {
        if(root->next)
        {
            tmp=root->next;
            while(tmp)
            {
                if(tmp->left)
                {
                    root->right->next=tmp->left;
                    break;
                }
                if(tmp->right)
                {
                    root->right->next=tmp->right;
                    break;
                }
                tmp=tmp->next;

            }  
        }
    }
    connect(root->right);
    connect(root->left);
}