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[CC150v4] 4.5 Find Next Node in BST


Write an algorithm to find the ‘next’ node (i.e., in-order successor) of a given node in a binary search tree where each node has a link to its parent.


  1. If current node have a right child, return the leftmost leaf of right child.

  2. If current node have no right child:

    1. If current is parent’s left child, then return parent node.

    2. If current is parent’s right child, look all the way up until find a right-turning parent.

    3. If all parent is not right-turning. Return null.


written by me

public static TreeNode inorderSucc(TreeNode e) {
    if (e == null)
        return null;
    if (e.right != null) {
        TreeNode p = e.right;
        while (p.left != null) {
            p = p.left;
        return p;
    } else {
        TreeNode p = e.parent;
        while (p != null && p.right == e) {
            e = p;
            p = e.parent;
        return p;