Web1 人赞同了该回答. 因为HashSet的底层是HashMap. 你没问对地方。. 为啥HashMap是O1?. 讨论时间复杂度O的时候不是关心最糟糕情况么?. 最糟糕情况不是,我put一个键值对的 … WebJul 15, 2014 · Would be O(a.length), as HashSet.contains and HashSet.remove are both O(1) (amortized). If you were to call. common.retainAll(Arrays.asList(b)); Then due to the O(n) contains on Arrays.ArrayList this would become O(a.length * b.length) - i.e. by spending O(n) copying the array to a HashSet you actually make the call to retainAll …
面试官:HashSet如何保证元素不重复? - 腾讯云
WebAug 8, 2015 · How does the contains-method find out if a certain object is/is not in a HashSet? I created a class with two instance variables. Then I put a few instances into a HashSet. I created the same instances again (with same instance variable values) and used them as the input for the contains-method. dyson multi tool hair dryer
HashSet (Java Platform SE 7 ) - Oracle
WebJul 17, 2015 · In order for a HashSet (or HashMap, for that matter) to properly locate your object, you need to override the hashCode() method so that two object which are equal have the same hashCode. The canonical way of doing this looks like this (assuming first and last can't be null, like your equals method assumes: @Override public int hashCode() { final … WebMay 20, 2024 · HashMap的时间复杂度分析. HashMap容器O (1)的查找时间复杂度只是其理想的状态,而这种理想状态需要由java设计者去保证。. 在由设计者保证了链表长度尽可能短的前提下,由于利用了数组结构,使得key的查找在O (1)时间内完成。. 可以将 HashMap分成两部分来看待,hash ... WebHashSet插入操作之前需要比较hashcode,那为什么插入的时间复杂度还是O1呢? 比较hashcode的操作不是遍历已有的吗? 显示全部 dyson multi function hair dryer