leetcode Populating Next Right Pointers in Each Node

/**
* 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) {
int nextLevel = 0;       //下一层需要访问几个节点
int tobePrint = 1;      //还需访问几个节点
queue<TreeLinkNode*> q;
if(root == NULL)
return;
q.push(root);
while(!q.empty())
{
TreeLinkNode* curNode = q.front();
if(curNode -> left != NULL)
{
nextLevel++;
q.push(curNode -> left);
}
if(curNode -> right != NULL)
{
nextLevel++;
q.push(curNode -> right);
}
q.pop();
tobePrint--;
if(tobePrint == 0) //当前行的最后一个节点
{
curNode -> next = NULL;
tobePrint = nextLevel;
nextLevel = 0;
}
else
{
curNode -> next = q.front();
}
}
}

};