TreeMap删除大于某个特定键的所有键 [英] TreeMap removing all keys greater than a certain key

问题描述

在项目中，我需要删除所有键值大于某个键的对象(键类型为Date，如果有关系的话).

In a project I need to remove all objects having key value greater than a certain key (key type is Date, if it matters).

据我所知，用Java实现的TreeMap是一棵红黑树，它是一个二进制搜索树.因此，删除子树时，我应该得到O(n).
但是我除了找到后视图并逐个删除需要O(logn)的任何其他方法之外，找不到其他方法.

As far as I know TreeMap implemented in Java is a red-black tree which is a binary search tree. So I should get O(n) when removing a subtree.
But I can't find any method to do this other than making a tail view and remove one by one, which takes O(logn).

实现此功能的任何好主意吗?我相信treeMap是要使用的正确的dataStructure，应该能够做到这一点.

Any good ideas implementing this function? I believe treeMap is the correct dataStructure to use and should be able to do this.

预先感谢

推荐答案

非常简单.而不是一个一个地删除条目，而是使用Map.clear()删除元素.在代码中:

Quite simple. Instead of removing the entries one-by-one, use Map.clear() to remove the elements. In code:

map.tailMap(key).clear();

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