Design HashSet — Bit Array or Chaining Approach

# Python — bit array (values 0..10^6)
class MyHashSet:
    def __init__(self): self.data = [False] * 1000001
    def add(self, key): self.data[key] = True
    def remove(self, key): self.data[key] = False
    def contains(self, key): return self.data[key]

// Java — chaining
class MyHashSet {
    private static final int SIZE = 1009;
    private LinkedList<Integer>[] set;
    public MyHashSet() { set = new LinkedList[SIZE]; }
    private int hash(int key) { return key % SIZE; }
    public void add(int key) {
        int h = hash(key);
        if (set[h] == null) set[h] = new LinkedList<>();
        if (!set[h].contains(key)) set[h].add(key);
    }
    public void remove(int key) {
        int h = hash(key);
        if (set[h] != null) set[h].remove((Integer)key);
    }
    public boolean contains(int key) {
        int h = hash(key);
        return set[h] != null && set[h].contains(key);
    }
}

// C++
class MyHashSet {
    static const int SIZE = 1009;
    vector<list<int>> buckets;
public:
    MyHashSet() : buckets(SIZE) {}
    void add(int key) {
        auto& b = buckets[key%SIZE];
        if (find(b.begin(),b.end(),key)==b.end()) b.push_back(key);
    }
    void remove(int key) { buckets[key%SIZE].remove(key); }
    bool contains(int key) {
        auto& b = buckets[key%SIZE];
        return find(b.begin(),b.end(),key) != b.end();
    }
};