Inorder Successor in BST

Source

• leetcode: 285

Given a binary search tree and a node in it, find the in-order successor of that
node in the BST.
Note: If the given node has no in-order successor in the tree, return null.

Java

public class Solution {
    public TreeNode inorderSuccessor(TreeNode root, TreeNode p) {
        TreeNode successor = null;
        while (root != null && root.val != p.val) {
            if (root.val > p.val) {
                successor = root;
                root = root.left;
            } else {
                root = root.right;
            }
        }

        if (root == null) {
            return null;
        }

        if (root.right == null) {
            return successor;
        }

        root = root.right;
        while (root.left != null) {
            root = root.left;
        }

        return root;
    }
}