LeetCode--Populating Next Right Pointers in Each Node II

同上题：

但是这题需要考虑好对当前节点的left和right的next指针如何设置。

/**
 * 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) {
        if(root == NULL){
            return;
        }
        TreeLinkNode *leftNext = NULL;
        TreeLinkNode *rightNext = NULL;
        TreeLinkNode *node = NULL;
        if(root->left){
            leftNext = root->right;
            node = root->next;
            while(!leftNext && node){
                if(node->left){
                    leftNext = node->left;
                    break;
                }
                if(node->right){
                    leftNext = node->right;
                    break;
                }
                node = node->next;
            }
            root->left->next = leftNext;
        }
        if(root->right){
            rightNext = NULL;
            node = root->next;
            while(!rightNext && node){
                if(node->left){
                    rightNext = node->left;
                    break;
                }
                if(node->right){
                    rightNext = node->right;
                    break;
                }
                node = node->next;
            }
            root->right->next = rightNext;
        }
        connect(root->right);
51         connect(root->left);
    }
};

root->left和root->right顺序不能变。