LeetCode: 341. 扁平化嵌套列表迭代器¶

2、解题思路¶

​ 设计一个栈，如果是一个list，就放到栈里面，栈顶存放一个数字

​ 但是，我们还需要知道他的下标，因此，我们就要同时保存下标

# """
# 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):
"""
:type nestedList: List[NestedInteger]
"""

self.stack = [[nestedList, 0]]

def next(self):
"""
:rtype: int
"""

self.hasNext()
nestedList, index = self.stack[-1]
self.stack[-1][1] += 1
return nestedList[index].getInteger()

def hasNext(self):
"""
:rtype: bool
"""

stack = self.stack
while stack:
nestedList, index = self.stack[-1]
if index == len(nestedList):
stack.pop()
else:
cur = nestedList[index]
if cur.isInteger():
return True
stack[-1][1] += 1
stack.append([cur.getList(), 0])
return False

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