LeetCode 235 Lowest Common Ancestor of a Binary Search Tree

题目

题意：判断BST中两个节点的最近的公共父节点

题解：递归的时候判断如果两个节点的值在父节点两边，那个这个父节点就是最近的公共父节点。否则按照二叉搜索树的规则递归下去。

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

         return lowestCommonAncestor(root->right,p,q);
    }
};