701. Insert into a Binary Search Tree
阿新 • • 發佈:2020-11-20
package LeetCode_701 /** * 701. Insert into a Binary Search Tree * https://leetcode.com/problems/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. Constraints: 1. The number of nodes in the tree will be in the range [0, 104]. 2. -108 <= Node.val <= 108 3. All the values Node.val are unique. 4. -108 <= val <= 108 5. It's guaranteed that val does not exist in the original BST. **/ class TreeNode(var `val`: Int) { var left: TreeNode? = null var right: TreeNode? = null } class Solution { /* * solution: recursion, Time:O(n), Space:O(logn) * */ fun insertIntoBST(root: TreeNode?, value: Int): TreeNode? { if (root == null) { return TreeNode(value) }if (root.`val` > value) { //value should be root's left child root.left = insertIntoBST(root.left, value) } else { root.right = insertIntoBST(root.right, value) } return root } }