lowestCommonAncestor.java

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if ((root.val >= p.val && root.val <= q.val) || (root.val <= p.val && root.val >= q.val)) {
            return root;
        } else {
            if (root.val > p.val) {
                return lowestCommonAncestor(root.left, p, q);
            } else {
                return lowestCommonAncestor(root.right, p ,q);
            }
        }   
    }
}