day-189.cpp

/*
  Insert into a Binary Search Tree


You are given the root node of a binary search tree (BST) and a value to insert
into the tree. Return the root node of the BST after the insertion. It is
guaranteed that the new value does not exist in the original BST.

Notice that there may exist multiple valid ways for the insertion, as long as
the tree remains a BST after insertion. You can return any of them.



Example 1:


Input: root = [4,2,7,1,3], val = 5
Output: [4,2,7,1,3,5]
Explanation: Another accepted tree is:

Example 2:

Input: root = [40,20,60,10,30,50,70], val = 25
Output: [40,20,60,10,30,50,70,null,null,25]
Example 3:

Input: root = [4,2,7,1,3,null,null,null,null,null,null], val = 5
Output: [4,2,7,1,3,5]

*/

// Simple solution using recursion
class Solution {
   public:
    TreeNode* insertIntoBST(TreeNode* root, int val) {
        if (!root) return new TreeNode(val);

        if (val > root->val) {
            root->right = insertIntoBST(root->right, val);
        } else {
            root->left = insertIntoBST(root->left, val);
        }
        return root;
    }
};