leetcode

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) {}
 * };
 */
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) {
		TreeLinkNode *head = NULL;
		TreeLinkNode *prev = NULL;
		TreeLinkNode *cur  = root;
		while(cur != NULL)
		{
			while(cur != NULL)
			{
				if(cur->left != NULL)
				{
					if(prev != NULL)
					{
						prev->next = cur->left;
					}
					else
					{
						head = cur->left;
					}
					prev = cur->left;
				}
				if(cur->right != NULL)
				{
					if(prev != NULL)
					{
						prev->next = cur->right;
					}
					else
					{
						head = cur->right;
					}
					prev = cur->right;
				}
				cur = cur->next;
			}
			cur = head;
			head = NULL;
			prev = NULL;
		}
    }
};