leetcode1286

import itertools
class CombinationIterator:

    def __init__(self, characters: str, combinationLength: int):
        self.lists = list(itertools.combinations(characters,combinationLength))
        self.index = 0

    def next(self) -> str:
        tp = self.lists[self.index]
        self.index += 1
        return ''.join(tp)

    def hasNext(self) -> bool:
        return self.index < len(self.lists)

直接调用itertools内置函数，快速生成符合条件的组合。

1286. Iterator for Combination