#1286

Iterator for Combination

pupil · 530 · lc medium +28 · 72.7% accepted · 1,390 likes · top 82%

Description

Implement a CombinationIterator class that lazily produces character combinations in lexicographic order:

- CombinationIterator(characters, combinationLength): Initializes the iterator with a sorted string characters of distinct lowercase letters and a target length combinationLength.
- next(): Returns the lexicographically next combination of length combinationLength.
- hasNext(): Returns true if more combinations remain.

Example 1:

Input

["CombinationIterator", "next", "hasNext", "next", "hasNext", "next", "hasNext"]

[["abc", 2], [], [], [], [], [], []]

Output

[null, "ab", true, "ac", true, "bc", false]

Example 2:

Explanation

CombinationIterator itr = new CombinationIterator("abc", 2);

itr.next(); // return "ab"

itr.hasNext(); // return True

itr.next(); // return "ac"

itr.hasNext(); // return True

itr.next(); // return "bc"

itr.hasNext(); // return False

Code

class CombinationIterator:

    def __init__(self, characters: str, combinationLength: int):
        

    def next(self) -> str:
        

    def hasNext(self) -> bool:
        


# Your CombinationIterator object will be instantiated and called as such:
# obj = CombinationIterator(characters, combinationLength)
# param_1 = obj.next()
# param_2 = obj.hasNext()

class CombinationIterator:

    def __init__(self, characters: str, combinationLength: int):
        

    def next(self) -> str:
        

    def hasNext(self) -> bool:
        


# Your CombinationIterator object will be instantiated and called as such:
# obj = CombinationIterator(characters, combinationLength)
# param_1 = obj.next()
# param_2 = obj.hasNext()