题解 | #二叉树的下一个结点#

static struct TreeLinkNode *pre = NULL;
static struct TreeLinkNode *ret = NULL;

//中序遍历,结果存入ret
void Inorder(struct TreeLinkNode *root, int val)
{
  if (!root || ret)
    return;
  Inorder(root->left, val);
  if (pre && pre->val == val)
    ret = root;
  pre = root;
  Inorder(root->right, val);
}

struct TreeLinkNode *GetNext(struct TreeLinkNode *pNode)
{
  struct TreeLinkNode *root;
  root = pNode;
  while (root->next)
    root = root->next;

  Inorder(root, pNode->val);
  return ret;
}