[permutation] permutation and combination algorithm #algorithm

permutation.js

function permuate(seq) {
  if (seq.length === 0) return [[]];
  const solutions = [];
  for(let i = 0; i < seq.length; ++i){
    const subSolutions = permuate(seq.filter((num, j) => j !== i));
    subSolutions.forEach(solution => solutions.push([seq[i]].concat(solution)));
  }
  return solutions;
}

function subsets(seq) {
  if(seq.length === 0) return [[]];
  const subsolutions = subsets(seq.slice(1));
  return subsolutions.concat(subsolutions.map(solution => [seq[0]].concat(solution)))
}