LCA BST

LowestCommonAncestorBST.java

package com.interviewbytes.trees;

public class LowestCommonAncestorBST {

    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if (root == null || p == root || q == root) return root;

        if ((p.val < root.val && q.val > root.val) || (q.val < root.val && p.val > root.val)) return root;

        if (p.val < root.val && q.val < root.val) return lowestCommonAncestor(root.left, p, q);

        return lowestCommonAncestor(root.right, p, q); //if(p.val > root.val && q.val > root.val)
    }
}

TreeNode.java

package com.interviewbytes.trees;

public class TreeNode {

    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int x) {
        val = x;
    }
}