[算法相关] Lowest Common Ancestor of a Binary Search Tree

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本文介绍了一种寻找二叉搜索树中两节点的最低公共祖先(LCA)的算法，并给出了具体的递归实现方式。文章通过实例展示了如何确定公共祖先，强调了二叉搜索树特性的重要性。

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235. Lowest Common Ancestor of a Binary Search Tree

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself).”

        _______6______
       /              \
    ___2__          ___8__
   /      \        /      \
   0      _4       7       9
         /  \
         3   5

For example, the lowest common ancestor (LCA) of nodes 2 and 8 is 6. Another example is LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.

如题，找到二叉搜索树中两个节点的最小公共父节点。如图所示，例如2和8 的最小公共父节点是6，其中2和4的最小公共父节点是2.

public class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root.val>p.val&&root.val>q.val){
            return lowestCommonAncestor(root.left, p,q);
        }else if(root.val<p.val&&root.val<q.val){
            return lowestCommonAncestor(root.right,p,q);
        }else
            return root;
    }
}

递归的思想……如果不是二叉搜索树怎么办？？