給你一個嵌套的整型列表。請你設計一個迭代器，使其能夠遍歷這個整型列表中的所有整數。

列表中的每一項或者為一個整數，或者是另一個列表。其中列表的元素也可能是整數或是其他列表。

示例 1:

輸入: [[1,1],2,[1,1]]
輸出: [1,1,2,1,1]
解釋: 通過重復調用 next 直到 hasNext 返回 false，next 返回的元素的順序應該是: [1,1,2,1,1]。

解題思路

先dfs嵌套列表，生成對應的list，然后對生成的列表進行迭代

代碼

/*** // This is the interface that allows for creating nested lists.* // You should not implement it, or speculate about its implementation* public interface NestedInteger {**     // @return true if this NestedInteger holds a single integer, rather than a nested list.*     public boolean isInteger();**     // @return the single integer that this NestedInteger holds, if it holds a single integer*     // Return null if this NestedInteger holds a nested list*     public Integer getInteger();**     // @return the nested list that this NestedInteger holds, if it holds a nested list*     // Return null if this NestedInteger holds a single integer*     public List<NestedInteger> getList();* }*/public class NestedIterator implements Iterator<Integer> {List<Integer> list=new ArrayList<>();Iterator<Integer> iterator;public NestedIterator(List<NestedInteger> nestedList) {dfs(nestedList);iterator=list.iterator();}void  dfs(List<NestedInteger> nestedList){for (NestedInteger nestedInteger : nestedList) {if(nestedInteger.isInteger())list.add(nestedInteger.getInteger());else dfs(nestedInteger.getList());}}@Overridepublic Integer next() {return iterator.next();}@Overridepublic boolean hasNext() {return  iterator.hasNext();}}
/*** Your NestedIterator object will be instantiated and called as such:* NestedIterator i = new NestedIterator(nestedList);* while (i.hasNext()) v[f()] = i.next();*/