[235 Lowest Common Ancestor of a Binary Search Tree] #leetcode

235_0801.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) < 1) {
            return root;
        } 
        
        if (root.val > p.val) {
            return lowestCommonAncestor(root.left, p, q);
        } else {
            return lowestCommonAncestor(root.right, p, q);
        }        
    }
}

public class Solution2 {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        while ((root.val - p.val) * (root.val - q.val) >= 1) {
            root = root.val > p.val? root.left : root.right;
        }
        return root;
    }
}