MyHashSet.java

package org.example;

// Time Complexity : O(1)
// Space Complexity : O(1)
// Did this code successfully run on Leetcode : Yes
// Any problem you faced while coding this : No


// Your code here along with comments explaining your approach
// The values are mapped to the array by using double hashing to resolve collisions here(hash1 and hash2). The primary array storage will save
// the address to the secondary array which in turn will save the elements in it post computing the hash value using hash2. The index range for
// both primary and the secondary array are taken based on square root method on the upper bound provided.


class MyHashSet {
    boolean [][] storage;
    int buckets;        // size of the primary array
    int bucketItems;    // size of the secondary array

    public MyHashSet() {
        this.buckets = 1000;
        this.bucketItems = 1000;
        this.storage = new boolean[1000][];
    }

    private int hash1 (int key){
        return key % 1000;
    }
    private int hash2 (int key){
        return key / 1000;
    }
    public void add(int key) {
        // Time Complexity : O(1)
        // Space Complexity : O(1)
        int bucket = hash1(key);
        int bucketItem = hash2(key);

        if(storage[bucket] == null){
            if(bucket == 0){        // condition to handle 10^6
                storage[bucket] = new boolean[bucketItems + 1];
            }else{
                storage[bucket] = new boolean[bucketItems];
            }

        }
        storage[bucket][bucketItem] = true;
    }

    public void remove(int key) {
        // Time Complexity : O(1)
        // Space Complexity : O(1)
        int bucket = hash1(key);
        int bucketItem = hash2(key);
        if(storage[bucket] == null) return;
        storage[bucket][bucketItem] = false;

    }

    public boolean contains(int key) {
        // Time Complexity : O(1)
        // Space Complexity : O(1)
        int bucket = hash1(key);
        int bucketItem = hash2(key);
        if(storage[bucket] == null) return false;
        return storage[bucket][bucketItem];
    }
}



/**
 * 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);
 */