Java 中对 LinkedList 调用 size() 的时间复杂度是多少? [英] What is the time complexity of a size() call on a LinkedList in Java?

问题描述

正如标题所问，我想知道 LinkedList 类中的 size() 方法是否需要分摊 O(1) 时间或 O(n) 时间.

As the title asks, I wonder if the size() method in the LinkedList class takes amortized O(1) time or O(n) time.

推荐答案

O(1).你可以谷歌搜索源代码，你会得到这样的:

It's O(1). You can google for the source code and you will come to such:

来自 http://www.docjar.com/html/api/java/util/LinkedList.java.html

我看过的所有 Collection 类都将大小存储为变量，并且不会遍历所有内容来获取它.

All of the Collection classes I have looked at store a the size as a variable and don't iterate through everything to get it.

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