Playground

Binary Search Tree

Visualize O(log n) search, insert, and delete with animated comparisons and inorder sorted output.

Binary Search Tree

A BST guarantees the BST property: every node in the left subtree is smaller, every node in the right subtree is larger. This enables O(log n) search, insert, and delete on a balanced tree.

class BSTNode {
val: number;
left: BSTNode | null; // val < this.val
right: BSTNode | null; // val > this.val
}
Insert
Search
Delete
EMPTY TREEInsert a number to begin
100%

INSERT

function insert(root, val):
if root == null:
return new Node(val)
if val < root.val:
root.left = insert(root.left, val)
else: // val >= root.val → RIGHT
root.right = insert(root.right, val)
return root

Console Output

NODES: 0
>Waiting for operations...

Want to see how the recursive code works?

Copy this code and paste it in the Recursion Tracer to visualize the call stack step-by-step.

OPEN TRACER ↗
class BSTNode {
  constructor(val) {
    this.val = val;
    this.left = null;
    this.right = null;
  }
}

function insert(root, val) {
  if (!root) return new BSTNode(val);
  if (val < root.val) root.left = insert(root.left, val);
  else if (val > root.val) root.right = insert(root.right, val);
  return root;
}

function buildBST(arr) {
  let root = null;
  for (const val of arr) root = insert(root, val);
  return root;
}

function inorder(node) {
  if (!node) return [];
  return [...inorder(node.left), node.val, ...inorder(node.right)];
}

// Build and traverse
const input = [5, 3, 7, 1, 4, 6, 8];
const root = buildBST(input);
console.log("Inorder:", inorder(root));
// Inorder of a BST always gives sorted output!