w-tree-binary-BreadthFirstValues.js

class Node {
  constructor(val) {
    this.val = val;
    this.left = null;
    this.right = null;
  }
}

//         a
//       /   \
//     b       c
//   / \         \
// d     e         f

const breadthFirstValues = (root) => {
  if (!root.val) return [];

  const queue = [root];
  const result = [];

  while (queue.length > 0) {
    const current = queue.shift();
    result.push(current.val);
    if (current.left) queue.push(current.left);
    if (current.right) queue.push(current.right);
  }
  console.log(result);
};

// queue shift: a => bc => cde => def
// stack pop: a => cb => ced => ce => c => f

const a = new Node("a");
const b = new Node("b");
const c = new Node("c");
const d = new Node("d");
const e = new Node("e");
const f = new Node("f");

a.left = b;
a.right = c;
b.left = d;
b.right = e;
c.right = f;

breadthFirstValues(a);