[leetcode] Populating Next Right Pointers in Each Node

最新推荐文章于 2021-09-24 12:05:40 发布

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本文详细阐述了如何使用常量额外空间填充二叉树节点的next指针，以指向其右侧相邻节点，并通过实例展示了操作过程。

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Given a binary tree

    struct TreeLinkNode {
      TreeLinkNode *left;
      TreeLinkNode *right;
      TreeLinkNode *next;
    }

Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.

Initially, all next pointers are set to NULL.

Note:

You may only use constant extra space.
You may assume that it is a perfect binary tree (ie, all leaves are at the same level, and every parent has two children).

For example,
Given the following perfect binary tree,

After calling your function, the tree should look like:

         1 -> NULL
       /  \
      2 -> 3 -> NULL
     / \  / \
    4->5->6->7 -> NULL

class Solution {
public:
    void connect(TreeLinkNode *root) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
        if(!root)
            return;
		TreeLinkNode** array=new TreeLinkNode*[10000];
		array[0]=root;
		int p,q,flag;
		for(p=0,q=1,flag=1 ; p!=q ; p++ ){
			if(p==flag){
				for(int i=p ; i<q-1 ; i++){
					array[i]->next=array[i+1];
				}
				flag=q;
			}
			if(array[p]->left)
				array[q++]=array[p]->left;
			if(array[p]->right)
				array[q++]=array[p]->right;
		}
	}
};