LeetCode 117. Populating Next Right Pointers in Each Node II

最新推荐文章于 2023-11-09 13:05:39 发布

LchinaM

最新推荐文章于 2023-11-09 13:05:39 发布

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针对Populating Next Right Pointers in Each Node问题的进阶版本，本文介绍了一种仅使用常数额外空间填充任意二叉树节点的方法。通过一次遍历即可完成所有节点的填充工作，最终使得每个节点指向其右侧相邻的节点。

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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,

After calling your function, the tree should look like:

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

answer:

class Solution {
public:
    void connect(TreeLinkNode *root) {
        TreeLinkNode temp(0);
        TreeLinkNode * index = &temp;
        TreeLinkNode * pre = root, * end = root, * end2 = root;
        if(!root) return;
        index->next = root;
        while(index != end){
            index = index->next;
            pre->next = NULL;
            if(index == NULL)
                return;
            if(index->left != NULL){
                end2->next = index->left;
                end2 = end2->next;
            }
            if(index->right != NULL){
                end2->next = index->right;
                end2 = end2->next;
            }
            if(index == end){
                pre = end;
                end = end2;
            }
        }
    }
};