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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。示例:
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)
提示:
0 <= key <= 106
104
次 add
、remove
和 contains
。
进阶:你可以不使用内建的哈希集合库解决此问题吗?
数组实现。
class MyHashSet:
def __init__(self):
"""
Initialize your data structure here.
"""
self.data = [False] * 1000001
def add(self, key: int) -> None:
self.data[key] = True
def remove(self, key: int) -> None:
self.data[key] = False
def contains(self, key: int) -> bool:
"""
Returns true if this set contains the specified element
"""
return self.data[key]
# Your MyHashSet object will be instantiated and called as such:
# obj = MyHashSet()
# obj.add(key)
# obj.remove(key)
# param_3 = obj.contains(key)
class MyHashSet {
private boolean[] data;
/** Initialize your data structure here. */
public MyHashSet() {
data = new boolean[1000001];
}
public void add(int key) {
data[key] = true;
}
public void remove(int key) {
data[key] = false;
}
/** Returns true if this set contains the specified element */
public boolean contains(int key) {
return data[key];
}
}
/**
* 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);
*/
SIZE
的数组,数组的每个位置是一个链表。class MyHashSet {
private static final int SIZE = 1000;
private LinkedList[] data;
/** Initialize your data structure here. */
public MyHashSet() {
data = new LinkedList[SIZE];
Arrays.fill(data, new LinkedList<Integer>());
}
public void add(int key) {
int index = hash(key);
Iterator<Integer> iterator = data[index].iterator();
while (iterator.hasNext()) {
Integer e = iterator.next();
if (e == key) return;
}
data[index].addFirst(key);
}
public void remove(int key) {
int index = hash(key);
ListIterator<Integer> iterator = data[index].listIterator();
while (iterator.hasNext()) {
Integer e = iterator.next();
if (e == key) iterator.remove();
}
}
/** Returns true if this set contains the specified element */
public boolean contains(int key) {
int index = hash(key);
Iterator<Integer> iterator = data[index].iterator();
while (iterator.hasNext()) {
Integer e = iterator.next();
if (e == key) return true;
}
return false;
}
private int hash(int key) {
return key % SIZE;
}
}
/**
* 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);
*/
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