Function powerset

recursion/powerset.js:21–36

(array, idx = null)

// runs in the same time/space complexity

function powerset(array, idx = null) {
    if (idx === null) {
      idx = array.length - 1;
    }
    if (idx < 0) {
      return [[]];
    }
    const ele = array[idx];
    const subsets = powerset(array, idx - 1);
    const length = subsets.length;
    for (let i = 0; i < length; i++) {
      const currentSubset = subsets[i];
      subsets.push(currentSubset.concat(ele));
    }
    return subsets;
  }
  
  const array = [];