LeetCode 1008. 【递归】构造二叉搜索树
原题链接
中等
作者:
大明湖的鱼
,
2021-01-19 20:42:15
,
所有人可见
,
阅读 254
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
TreeNode* bstFromPreorder(vector<int>& preorder) {
TreeNode* root = nullptr;
for(auto it : preorder){
root = add(root,it);
}
return root;
}
TreeNode* add(TreeNode* root, int num){
if(root == nullptr) {
TreeNode* tmp = new TreeNode(num);
return tmp;
}
if(root->val > num) root->left = add(root->left,num);
else root->right = add(root->right,num);
return root;
}
};