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  • 【leetcode】341. Flatten Nested List Iterator

    题目如下:

    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:

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

    Example 2:

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

    解题思路:题目不难,递归解析即可。

    代码如下:

    # """
    # 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):
            """
            Initialize your data structure here.
            :type nestedList: List[NestedInteger]
            """
            self.val = []
    
            def recursive(nestedList):
                for item in nestedList:
                    if item.isInteger():
                        self.val.append(item.getInteger())
                    else:
                        recursive(item.getList())
    
            recursive(nestedList)
                        
            
        def next(self):
            """
            :rtype: int
            """
            return self.val.pop(0)
            
    
        def hasNext(self):
            """
            :rtype: bool
            """
            return 0 != len(self.val)
            
    
    # Your NestedIterator object will be instantiated and called as such:
    # i, v = NestedIterator(nestedList), []
    # while i.hasNext(): v.append(i.next())
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  • 原文地址:https://www.cnblogs.com/seyjs/p/11926360.html
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