Power Set

• n x 2^n, n x 2^n

function powerset(arr) {
  let answer = [[]];
  
  for (const n of arr) {
    const temp = [];
    for (const el of answer) {
      const next = [...el, n];
      temp.push(next);
    }
    answer.push(...temp);
  }
  
  return answer;
}

// Do not edit the line below.
exports.powerset = powerset;

• simpler

function powerset(arr) {
  let answer = [[]];
  
  for (const n of arr) {
	const answerLenBeforeThisIter = answer.length;
    for (let i = 0; i < answerLenBeforeThisIter; i++) {
      answer.push(answer[i].concat(n));
    }
  }
  
  return answer;
}

// Do not edit the line below.
exports.powerset = powerset;