Problem
Solution
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HashSet using Array
Certification: Basic Level
Accuracy: 25%
Submissions: 4
Points: 8
Write a Java program to implement a HashSet data structure using arrays. The implementation should support the following operations: add(key), remove(key), contains(key), and size(). The HashSet should be able to store integers.
Example 1
- Input:
["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"]
[[], [1], [2], [1], [3], [2], [2], [2], [2]] - Output: [null, null, null, true, false, null, true, null, false]
- Explanation:
- MyHashSet myHashSet = new MyHashSet();
- myHashSet.add(1); // set = [1]
- myHashSet.add(2); // set = [1, 2]
- myHashSet.contains(1); // return True
- myHashSet.contains(3); // return False, (not found)
- myHashSet.add(2); // set = [1, 2]
- myHashSet.contains(2); // return True
- myHashSet.remove(2); // set = [1]
- myHashSet.contains(2); // return False, (already removed)
Example 2
- Input:
["MyHashSet", "add", "remove", "add", "contains", "contains", "add", "remove", "contains", "size"]
[[], [10], [10], [20], [10], [20], [30], [20], [20], []] - Output: [null, null, null, null, false, true, null, null, false, 2]
- Explanation: Various operations are performed on the hash set, and the final size is 2.
Constraints
- 0 ≤ key ≤ 10^6
- At most 10^4 calls will be made to add, remove, contains, and size
- Time Complexity: O(1) average case for all operations
- Space Complexity: O(n) where n is the capacity of the hash set
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Solution Hints
- Use an array of boolean values or a linked list array to implement the hash set
- Implement a hash function to map keys to array indices
- Handle collisions using a technique like chaining or open addressing
- For simplicity, you can use modulo operation for hashing
- Consider resizing the array when the load factor exceeds a threshold