C#•2y ago

❔ How come shall the data type be int, not TreeNode?

https://leetcode.com/problems/validate-binary-search-tree/?envType=study-plan&id=level-1 It's about this question I have tried the below solution

public class Solution {
    public bool IsValidBST(TreeNode root) {
        List<TreeNode> l = new List<TreeNode>();
        for(int i = 0; i < l.Count-1; i++){
            if(l[i] >= l[i+1]){
                return false;
            }

        }
        return Helper(root,l);
    }

    public List<TreeNode> Helper(TreeNode root, List<TreeNode> l){
        List<TreeNode> l = new List<TreeNode>();

        if(root != null){
            
          return l;
        }

            l.Add(Helper(root.left));
            l.Add(root.val);
            l.Add(Helper(root.right));
        return l;

        
    }
}

public class Solution {
    public bool IsValidBST(TreeNode root) {
        List<TreeNode> l = new List<TreeNode>();
        for(int i = 0; i < l.Count-1; i++){
            if(l[i] >= l[i+1]){
                return false;
            }

        }
        return Helper(root,l);
    }

    public List<TreeNode> Helper(TreeNode root, List<TreeNode> l){
        List<TreeNode> l = new List<TreeNode>();

        if(root != null){
            
          return l;
        }

            l.Add(Helper(root.left));
            l.Add(root.val);
            l.Add(Helper(root.right));
        return l;

        
    }
}

`
I know the logic is not right here, but some answers like this one set the data type of the List variable to

int, not TreeNode` like I did. : https://leetcode.com/problems/validate-binary-search-tree/solutions/3327674/simple-c-code/?envType=study-plan&id=level-1&languageTags=csharp Could anyone kindly explain to me why it is int, not TreeNode?

LeetCode

Validate Binary Search Tree - LeetCode

Can you solve this real interview question? Validate Binary Search Tree - Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: * The left subtree of a node contains only nodes with keys less than the node's key. * The right subtree of a node contains only nodes with keys gre...

LeetCode

Simple C# code - Validate Binary Search Tree - LeetCode

View VikasSinghThakur07's solution of Validate Binary Search Tree on LeetCode, the world's largest programming community.

1 Reply

Accord•2y ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

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❔ How come shall the data type be int, not TreeNode?