Validating A Binary Search Tree In O(n) Time Complexity
Validating a Binary Search Tree (BST) in O(n) time complexity. A BST is valid if for every node, its value is greater than all values in its left subtree and less than all values in its right subtree.
Problem
TC: O(n), SC: O(n)
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public boolean isValidBST(TreeNode root) {
return isValid(root,-1001,1001);
}
// inorder dfs
public boolean isValid(TreeNode root,int l, int r){
if(root ==null) ret...