leetcode 117. 填充每个节点的下一个右侧节点指针 II

/*
// Definition for a Node.
class Node {
public:
    int val;
    Node* left;
    Node* right;
    Node* next;

    Node() : val(0), left(NULL), right(NULL), next(NULL) {}

    Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}

    Node(int _val, Node* _left, Node* _right, Node* _next)
        : val(_val), left(_left), right(_right), next(_next) {}
};
*/

class Solution {
public:
	Node* connect(Node* root) {
		queue<Node*> q;
		if (root != NULL) 
			q.push(root);
		while (!q.empty()) 
		{
			int size = q.size();
			Node *node;
			Node *pre_node;
			for (int i = 0; i < size; i++)
			{
				if (i == 0)
				{
					node = q.front();
					q.pop();
					pre_node = node;
				}
				else
				{
					node = q.front();
					q.pop();
					pre_node->next = node;
					pre_node = pre_node->next;
				}
                if(node->left)
                {
                    q.push(node->left);
                }
                if(node->right)
                {
                    q.push(node->right);
                }
			}
			pre_node->next == NULL;
		}
		return root;

	}
};

害，还是要慢慢刷题