Leetcode 700. Search in a Binary Search Tree

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

• Iterative

/**
 * 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* searchBST(TreeNode* root, int val) {
        TreeNode* current = root;
        while(current) {
            if(current->val == val) {
                return current;
            }
            else if(current->val < val) {
                current = current->right;
            }
            else {
                current = current->left;
            }
        }
        return NULL;
    }
};

• Recursive

/**
 * 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* searchBST(TreeNode* root, int val) {
        if(!root) {
            return NULL;
        }
        else if(root->val == val) {
            return root;
        }
        else if(root->val < val) {
            return searchBST(root->right, val);
        }
        else {
            return searchBST(root->left, val);
        }
    }
};

Reference

1. https://leetcode.com/problems/search-in-a-binary-search-tree/description/