Function bfs

javascript/0103-binary-tree-zigzag-level-order-traversal.js:30–42

(queue, isZigZag, levels)

};

const bfs = (queue, isZigZag, levels) => {
    for (let level = queue.size(); 0 < level; level--) {
        /* Time O(WIDTH) */
        const { left, val, right } = queue.dequeue();

        if (left) queue.enqueue(left); /* Space O(WIDTH) */
        if (right) queue.enqueue(right); /* Space O(WIDTH) */

        levels.push(val); /* Space O(N) */
    }

    if (!isZigZag) levels.reverse();
};