题目所属分类

华为校招

原题链接

不使用任何内建的哈希表库设计一个哈希集合（HashSet）。

实现 MyHashSet 类：

void add(key) 向哈希集合中插入值 key 。
bool contains(key) 返回哈希集合中是否存在这个值 key 。
void remove(key) 将给定值 key 从哈希集合中删除。如果哈希集合中没有这个值，什么也不做。

代码案例：输入：
[“MyHashSet”, “add”, “add”, “contains”, “contains”, “add”, “contains”, “remove”, “contains”]
[[], [1], [2], [1], [3], [2], [2], [2], [2]]
输出：
[null, null, null, true, false, null, true, null, false]
解释：
MyHashSet myHashSet = new MyHashSet();
myHashSet.add(1); // set = [1]
myHashSet.add(2); // set = [1, 2]
myHashSet.contains(1); // 返回 True
myHashSet.contains(3); // 返回 False ，（未找到）
myHashSet.add(2); // set = [1, 2]
myHashSet.contains(2); // 返回 True
myHashSet.remove(2); // set = [1]
myHashSet.contains(2); // 返回 False ，（已移除）

0 <= key <= 10^6
最多调用 10^4 次 add、remove 和 contains

题解

class MyHashSet {int N = (int)10e4+3;LinkedList<Node> [] h = new LinkedList[N];class Node {private int key;private Node(int key) {this.key = key;}}public MyHashSet() {for(int i = 0 ; i < N; i++){h[i] = new LinkedList<>();}}public void add(int key) {int k = hash(key) ; int t = find(k,key);if(t == -1){h[k].add(new Node(key));} }public void remove(int key) {int k = hash(key);int t = find(k ,key);if(t > -1) h[k].remove(t);}public boolean contains(int key) {int k = hash(key);int t = find(k,key);return t != -1 ;}public int hash(int x){return (x %N + N) % N;}public int find (int k ,int x){for(int i = 0 ; i < h[k].size();i++){if(h[k].get(i).key == x){return i ;}}return - 1;}
}/*** Your MyHashSet object will be instantiated and called as such:* MyHashSet obj = new MyHashSet();* obj.add(key);* obj.remove(key);* boolean param_3 = obj.contains(key);*/

class MyHashSet {int N = (int)10e4+3;LinkedList<Node> [] h = new LinkedList[N];class Node {private int key;private Node(int key) {this.key = key;}}public MyHashSet() {for(int i = 0 ; i < N; i++){h[i] = new LinkedList<>();}}public void add(int key) {int k = hash(key) ; int t = find(k,key);if(t == -1){h[k].add(new Node(key));} }public void remove(int key) {int k = hash(key);int t = find(k ,key);if(t > -1) h[k].remove(t);}public boolean contains(int key) {int k = hash(key);int t = find(k,key);return t != -1 ;}public int hash(int x){return (x %N + N) % N;}public int find (int k ,int x){for(int i = 0 ; i < h[k].size();i++){if(h[k].get(i).key == x){return i ;}}return - 1;}
}/*** Your MyHashSet object will be instantiated and called as such:* MyHashSet obj = new MyHashSet();* obj.add(key);* obj.remove(key);* boolean param_3 = obj.contains(key);*/