LeetCode 1008 前序遍历构造二叉搜索树

• 分析

  简单递归遍历

• 代码

class Solution {
public:
    TreeNode* bstFromPreorder(vector<int>& preorder) {
        TreeNode* root = nullptr;
        int size = preorder.size();
        for(int i = 0; i < size; i++){
            root = insert(root, preorder[i]);
        }

        return root;
    }    

    TreeNode* insert(TreeNode* root, int val){
        if(root == nullptr) return new TreeNode(val);

        if(root -> val < val){
            root -> right = insert(root -> right, val);
        }else if(root -> val > val){
            root -> left = insert(root -> left, val);
        }

        return root;
    }
};