createSubset.js

export default function createSubset(array) {
  class Node {
    constructor(level, antiparticle = false) {
      this.level = level;
      this.v = array[level];
      this.l = array[level + 1] && new Node(level + 1);
      this.r = array[level + 1] && new Node(level + 1, true);
      this.antiparticle = antiparticle;
      this.visited = false;
    }
  }
  const root = new Node(-1);
  const records = [];
  const stack = [];
  const record = stack => records.push(stack.map(({v, antiparticle}) => !antiparticle && v).filter(Boolean));
  let cursor = root;
  while (cursor) {
    if (cursor.l && !cursor.l.visited) {
      cursor.visited = true;
      stack.push(cursor);
      cursor = cursor.l;
    } else if (cursor.r && !cursor.r.visited) {
      stack.push(cursor);
      cursor.visited = true;
      cursor = cursor.r;
    } else if (cursor.visited) {
      cursor = stack.pop();
    } else {
      cursor.visited = true;
      record(stack.concat(cursor));
    }
  }
  return records;
}