Package g0201_0300.s0235_lowest_common_ancestor_of_a_binary_search_tree

Class Solution

java.lang.Object

g0201_0300.s0235_lowest_common_ancestor_of_a_binary_search_tree.Solution

public class Solution
extends Object

235 - Lowest Common Ancestor of a Binary Search Tree.<p>Easy</p> <p>Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.</p> <p>According to the <a href="https://en.wikipedia.org/wiki/Lowest_common_ancestor" target="_top">definition of LCA on Wikipedia</a>: \u201cThe lowest common ancestor is defined between two nodes <code>p</code> and <code>q</code> as the lowest node in <code>T</code> that has both <code>p</code> and <code>q</code> as descendants (where we allow <strong>a node to be a descendant of itself</strong> ).\u201d</p> <p><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2018/12/14/binarysearchtree_improved.png" alt="" /></p> <p><strong>Input:</strong> root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8</p> <p><strong>Output:</strong> 6</p> <p><strong>Explanation:</strong> The LCA of nodes 2 and 8 is 6.</p> <p><strong>Example 2:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2018/12/14/binarysearchtree_improved.png" alt="" /></p> <p><strong>Input:</strong> root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong> The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> root = [2,1], p = 2, q = 1</p> <p><strong>Output:</strong> 2</p> <p><strong>Constraints:</strong></p> <ul> <li>The number of nodes in the tree is in the range <code>[2, 10⁵]</code>.</li> <li><code>-10⁹ <= Node.val <= 10⁹</code></li> <li>All <code>Node.val</code> are <strong>unique</strong>.</li> <li><code>p != q</code></li> <li><code>p</code> and <code>q</code> will exist in the BST.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
TreeNode	lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

lowestCommonAncestor

public TreeNode lowestCommonAncestor(TreeNode root,
 TreeNode p,
 TreeNode q)