341. Flatten Nested List Iterator【M】【42】

最新推荐文章于 2019-08-01 16:22:25 发布

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最新推荐文章于 2019-08-01 16:22:25 发布

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本文介绍了一种算法，用于将嵌套的整数列表展平。通过递归地处理列表中的每个元素，无论是整数还是另一个列表，该算法能够确保所有元素按正确的顺序返回。

Given a nested list of integers, implement an iterator to flatten it.

Each element is either an integer, or a list -- whose elements may also be integers or other lists.

Example 1:
Given the list [[1,1],2,[1,1]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].

Example 2:
Given the list [1,[4,[6]]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].

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# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
#class NestedInteger(object):
#    def isInteger(self):
#        """
#        @return True if this NestedInteger holds a single integer, rather than a nested list.
#        :rtype bool
#        """
#
#    def getInteger(self):
#        """
#        @return the single integer that this NestedInteger holds, if it holds a single integer
#        Return None if this NestedInteger holds a nested list
#        :rtype int
#        """
#
#    def getList(self):
#        """
#        @return the nested list that this NestedInteger holds, if it holds a nested list
#        Return None if this NestedInteger holds a single integer
#        :rtype List[NestedInteger]
#        """

class NestedIterator(object):

    def __init__(self, nestedList):

        l = nestedList
        self.res = []

        if not l:
            return

        while l != []:
            i = l.pop(0)
            if i.isInteger():
                self.res += i.getInteger(),
            else:
                l = i.getList() + l

        """
        Initialize your data structure here.
        :type nestedList: List[NestedInteger]
        """

    def next(self):
        return self.res.pop(0)
        """
        :rtype: int
        """

    def hasNext(self):
        return self.res != []
        """
        :rtype: bool
        """

# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())