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 callingnext repeatedly untilhasNext returns false, the order of elements returned bynext should be:[1,1,2,1,1]. Example 2:
Input:[1,[4,[6]]] Output:[1,4,6] Explanation:By callingnext repeatedly untilhasNext returns false, the order of elements returned bynext should be:[1,4,6]. 给你一个嵌套的整型列表。请你设计一个迭代器，使其能够遍历这个整型列表中的所有整数。列表中的每一项或者为一个整数，或者是另一个列表。其中列表的元素也可能是整数或是其他列表。
- 题目要求实现一个嵌套版的数组。可以用
[]int实现，也可以用链表实现。笔者此处用链表实现。外层构造一个一维数组，一维数组内部每个元素是一个链表。额外还需要记录这个嵌套链表在原数组中的index索引。Next()实现比较简单，取出对应的嵌套节点。HasNext()方法则感觉嵌套节点里面的index信息判断是否还有next元素。
/** * // This is the interface that allows for creating nested lists. * // You should not implement it, or speculate about its implementation * type NestedInteger struct { * } * * // Return true if this NestedInteger holds a single integer, rather than a nested list. * func (this NestedInteger) IsInteger() bool {} * * // Return the single integer that this NestedInteger holds, if it holds a single integer * // The result is undefined if this NestedInteger holds a nested list * // So before calling this method, you should have a check * func (this NestedInteger) GetInteger() int {} * * // Set this NestedInteger to hold a single integer. * func (n *NestedInteger) SetInteger(value int) {} * * // Set this NestedInteger to hold a nested list and adds a nested integer to it. * func (this *NestedInteger) Add(elem NestedInteger) {} * * // Return the nested list that this NestedInteger holds, if it holds a nested list * // The list length is zero if this NestedInteger holds a single integer * // You can access NestedInteger's List element directly if you want to modify it * func (this NestedInteger) GetList() []*NestedInteger {} */typeNestedIteratorstruct { stack*list.List } typelistIndexstruct { nestedList []*NestedIntegerindexint } funcConstructor(nestedList []*NestedInteger) *NestedIterator { stack:=list.New() stack.PushBack(&listIndex{nestedList, 0}) return&NestedIterator{stack} } func (this*NestedIterator) Next() int { if!this.HasNext() { return-1 } last:=this.stack.Back().Value.(*listIndex) nestedList, i:=last.nestedList, last.indexval:=nestedList[i].GetInteger() last.index++returnval } func (this*NestedIterator) HasNext() bool { stack:=this.stackforstack.Len() >0 { last:=stack.Back().Value.(*listIndex) nestedList, i:=last.nestedList, last.indexifi>=len(nestedList) { stack.Remove(stack.Back()) } else { val:=nestedList[i] ifval.IsInteger() { returntrue } last.index++stack.PushBack(&listIndex{val.GetList(), 0}) } } returnfalse }