insert-into-a-binary-search-tree.java

// 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]
//
//
//  
// Constraints:
//
//
// 	The number of nodes in the tree will be in the range [0, 104].
// 	-108 <= Node.val <= 108
// 	All the values Node.val are unique.
// 	-108 <= val <= 108
// 	It's guaranteed that val does not exist in the original BST.
//
//


/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public TreeNode insertIntoBST(TreeNode root, int val) {
        if (root == null) return new TreeNode(val);
        if (root.val > val) root.left = insertIntoBST(root.left, val);
        else root.right = insertIntoBST(root.right, val);
        return root;
    }
}