1282. Group the People Given the Group Size They Belong To - LeetCode

class Solution:
    def groupThePeople(self, groupSizes: list[int]) -> list[list[int]]:
        ht: dict[int, list[int]] = {}
        for i, s in enumerate(groupSizes):
            ht[s] = ht.get(s, [])
            ht[s].append(i)
        result = []
        for s, l in ht.items():
            result.extend([l[i : i + s] for i in range(0, len(l), s)])
        return result