这题和701. Insert into a Binary Search Tree 解体思路一样。
/**
* 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* getbst(TreeNode* root,int val){
if(root == NULL)
return new TreeNode(val);//递归返回条件
if(root->val < val){
root->right = getbst(root->right,val);
}else{
root->left = getbst(root->left,val);
}
return root;
}
TreeNode* bstFromPreorder(vector<int>& preorder) {
if(preorder.size() == 0)
return NULL;
TreeNode* root = new TreeNode(preorder[0]);
for(int i = 1;i<preorder.size();i++){
getbst(root,preorder[i]);
}
return root;
}
};