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Populating Next Right Pointers in Each Node II

2024-07-06 10:52:52   224人阅读

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
/**
 * 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) 
    {
        vector<TreeLinkNode*> list;
        if(root==NULL) return;
        
        list.push_back(root);
        while(list.size()>0)
        {
            vector<TreeLinkNode*> children;
            for(int i=0;i<list.size();i++)
            {
                if(list[i]->left!=NULL) 
                {
                    children.push_back(list[i]->left);
                    if(children.size()>1) children[children.size()-2]->next=children[children.size()-1];
                }
                if(list[i]->right!=NULL) 
                {
                    children.push_back(list[i]->right);
                    if(children.size()>1) children[children.size()-2]->next=children[children.size()-1];
                }
            }
            list=children;
        }
    }
};

 


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