Tree Next#10146

Tree Next

1 second

128 megabytes

Easy

Binary search tree is given. Find the next element after the given one in the tree.

Definition of a tree:

// Java
class TreeNode
{
public:
  int val;
  TreeNode left, right, parent;
  TreeNode(int x, TreeNode prev) {
    val = x;
    left = NULL; 
    right = NULL;
    parent = prev;
};

// C++
class TreeNode
{
public:
  int val;
  TreeNode *left, *right, *parent;
  TreeNode(int x, TreeNode *prev = NULL) : val(x), left(NULL), right(NULL), parent(prev) {};
};

Implement function Next that returns pointer to the next element in a tree. If next element does not exist, return NULL.

// Java
TreeNode Next(TreeNode tree)

// C++
TreeNode* Next(TreeNode *tree)

Examples

Function Next with tree pointing to $8$ returns pointer to the node with value $9$ .