[Leetcode]Populating Next Right Pointers in Each Node

思路：逐层处理

/** * 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) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        while(root != NULL && root->left != NULL)        {            TreeLinkNode *cur = root;            while(cur != NULL)            {                cur->left->next = cur->right;                cur->right->next = cur->next != NULL ? cur->next->left : NULL;                cur = cur->next;            }            root = root->left;        }    }};