Java实现 LeetCode 341 扁平化嵌套列表迭代器

嵌套列表迭代器"/>

Java实现 LeetCode 341 扁平化嵌套列表迭代器

341. 扁平化嵌套列表迭代器

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。

示例 1:

输入: [[1,1],2,[1,1]]
输出: [1,1,2,1,1]
解释: 通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,1,2,1,1]。
示例 2:

输入: [1,[4,[6]]]
输出: [1,4,6]
解释: 通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,4,6]。

/*** // 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> {private List<Integer> list = new ArrayList<>();private int index;private void add(List<NestedInteger> nestedList) {for (NestedInteger nestedInteger : nestedList) {if (nestedInteger.isInteger()) {list.add(nestedInteger.getInteger());} else {add(nestedInteger.getList());}}}public NestedIterator(List<NestedInteger> nestedList) {add(nestedList);}@Overridepublic Integer next() {return list.get(index++);}@Overridepublic boolean hasNext() {return index < list.size();}
}/*** Your NestedIterator object will be instantiated and called as such:* NestedIterator i = new NestedIterator(nestedList);* while (i.hasNext()) v[f()] = i.next();*/