341. Flatten Nested List Iterator

最新推荐文章于 2022-05-08 19:51:35 发布

原创最新推荐文章于 2022-05-08 19:51:35 发布 · 309 阅读

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本文介绍了一种处理嵌套列表的方法，通过递归遍历将所有整数元素收集到ArrayList中，并提供了一个简单的迭代器来按顺序访问这些元素。

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:
Given the list [[1,1],2,[1,1]],

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

Example 2:
Given the list [1,[4,[6]]],

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

嵌套的容器，设计一个迭代器，以便顺序访问里面的元素。

一个个判断逻辑有些混乱，直接递归全部取出来，塞入ArrayList，返回ArrayList的迭代器就好了。

public class NestedIterator implements Iterator<Integer> 
{

	ArrayList<Integer> arraylist;
	Iterator<Integer> it;
    public NestedIterator(List<NestedInteger> nestedList)
    {
       arraylist=new ArrayList<>();
       getval(nestedList);
       it=arraylist.iterator();
    }

    @Override
    public Integer next()
    {
    	return it.next();
    }

    @Override
    public boolean hasNext()
    {
        return it.hasNext();
    }

	
	public void getval(List<NestedInteger> nestedList)
	{
		for(NestedInteger nestinteger : nestedList)
			if(nestinteger.isInteger())
				arraylist.add(nestinteger.getInteger());
			else {
				getval(nestinteger.getList());
			}
	}
	
	
}