251. Flatten 2D Vector

最新推荐文章于 2021-09-22 14:42:08 发布

mingyangdai

最新推荐文章于 2021-09-22 14:42:08 发布

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分类专栏：数据结构&算法 leetcode 文章标签：算法

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Implement an iterator to flatten a 2d vector.

For example,

Given 2d vector =

[

[1,2],

[3],

[4,5,6]

]

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,2,3,4,5,6].

Follow up:

As an added challenge, try to code it using only iterators in C++ or iterators in Java.

对比了discuss 仍然觉得我写的好…

beats 84.91% 下面就是我的code

public class Vector2D implements Iterator<Integer> {

    private Iterator<List<Integer>> all;
    private Iterator<Integer> cur;
    
    public Vector2D(List<List<Integer>> vec2d) {
        all = vec2d.iterator();
    }

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

    @Override
    public boolean hasNext() {
        if (cur != null && cur.hasNext()) return true;
        //1.
        while(all.hasNext()){
            cur = all.next().iterator();
            if(cur.hasNext()) return true;
        }
        return false;
    }
}

1.为什么使用while 因为有可能有这种输入

[

[1,2],

[],

[4,5,6]

]