10-20 leetcode 0341

题目

You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it.

Implement the NestedIterator class:

NestedIterator(List nestedList) Initializes the iterator with the nested list nestedList.
int next() Returns the next integer in the nested list.
boolean hasNext() Returns true if there are still some integers in the nested list and false otherwise.

题解

就其实直接按照题意遍历就行了

class NestedInteger:
    def isInteger(self) -> bool:
        """
        @return True if this NestedInteger holds a single integer, rather than a nested list.
        """

    def getInteger(self) -> int:
        """
        @return the single integer that this NestedInteger holds, if it holds a single integer
        Return None if this NestedInteger holds a nested list
        """

    def getList(self) -> list["NestedInteger"]:
        """
        @return the nested list that this NestedInteger holds, if it holds a nested list
        Return None if this NestedInteger holds a single integer
        """


class NestedIterator:
    def __init__(self, nestedList: list[NestedInteger]):
        self._data = nestedList

    def next(self) -> int:
        return self._data.pop(0).getInteger()

    def hasNext(self) -> bool:
        while self._data:
            if self._data[0].isInteger():
                return True
            self._data = self._data[0].getList() + self._data[1:]
        return False

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