700. 二叉搜索树中的搜索

一、递归

class Solution {
public:
    TreeNode* searchBST(TreeNode* root, int val) {
        if(!root)return NULL;
        if(root->val==val)return root;
        if(root->val>val)
            return searchBST(root->left,val);
        if(root->val<val)
            return searchBST(root->right,val);
        return NULL;
    }
};

二、迭代法

class Solution {
public:
    TreeNode* searchBST(TreeNode* root, int val) {
        while (root != NULL) {
            if (root->val > val) root = root->left;
            else if (root->val < val) root = root->right;
            else return root;
        }
        return NULL;
    }
};