面试题68 - I. 二叉搜索树的最近公共祖先

[fireairforce]

递归找就行了:

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