剑指Offer——二叉树的下一个结点

 1 /*
 2 struct TreeLinkNode {
 3     int val;
 4     struct TreeLinkNode *left;
 5     struct TreeLinkNode *right;
 6     struct TreeLinkNode *next;
 7     TreeLinkNode(int x) :val(x), left(NULL), right(NULL), next(NULL) {
 8 
 9     }
10 };
11 */
12 class Solution {
13 public:
14     TreeLinkNode* GetNext(TreeLinkNode* pNode) {
15         if(pNode->right == NULL) {
16             if(pNode->next == NULL) return NULL;
17             TreeLinkNode* p1 = pNode;
18             TreeLinkNode* p2 = pNode->next;
19             while(p2 && p2->right == p1) {
20                 p1 = p1->next;
21                 p2 = p1->next;
22             }
23             if(p2) return p2;
24             return NULL;
25         }
26         TreeLinkNode* nextNode = pNode->right;
27         while(nextNode->left) {
28             nextNode = nextNode->left;
29         }
30         return nextNode;
31     }
32 };