问题
As the title asks, I wonder if the size() method in the LinkedList class takes amortized O(1) time or O(n) time.
回答1:
It's O(1). You can google for the source code and you will come to such:
From http://www.docjar.com/html/api/java/util/LinkedList.java.html
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.
回答2:
O(1) as you would have found had you looked at the source code...
From LinkedList:
private transient int size = 0;
...
/**
* Returns the number of elements in this list.
*
* @return the number of elements in this list
*/
public int size() {
return size;
}
来源：https://stackoverflow.com/questions/863469/what-is-the-time-complexity-of-a-size-call-on-a-linkedlist-in-java