[JS] Binary tree height

binaryTreeHeight.js

// Problem: https://www.hackerrank.com/challenges/tree-height-of-a-binary-tree/problem

function getHeight(head) {  
  if(!head) return -1;
  const heights = new Set();
  DFS(head, -1, heights); 
  
  return Math.max(...heights);
}


function DFS(node, height, heights) { 
  if(!node) { 
    heights.add(height);
    return;
  }
  
  DFS(node.right, height + 1, heights); 
  DFS(node.left, height + 1, heights); 
}


// ------------------------- Test ---------------------------//

class Node {
  constructor(data) {
    this.data = data;
    this.left = null;
    this.right = null;
  }
}
//     head 
//    /   \
//  node1 node2
//         / \
//     node3  node4
//       \
//       node5
console.log(getHeight(null));  // -1
const head = new Node();
console.log(getHeight(head));  // 0
const node1 = new Node();
head.left = node1;
console.log(getHeight(head));  // 1
const node2 = new Node();
head.right = node2;
console.log(getHeight(head));  // 1
const node3 = new Node();
const node4 = new Node();
const node5 = new Node();
node2.left = node3;
node2.right = node4;
node3.right = node5;
console.log(getHeight(head)); // 3