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Solution 11: Binary Set Logic (Design HashSet)

Approach Explanation

Like the HashMap, we use separate chaining with a prime number of buckets to minimize collisions.

Step-by-Step Logic

  1. __init__: self.size = 769, self.buckets = [[] for _ in range(self.size)].
  2. _hash(key): key % self.size.
  3. add(key):
    • Check if key is in self.buckets[idx].
    • If not, append it.
  4. contains(key):
    • Return True if key is in self.buckets[idx].
  5. remove(key):
    • If key is in self.buckets[idx], remove it.

Complexity

  • Time Complexity: O(N / K).
  • Space Complexity: O(N + K).

Code

class MyHashSet:
    def __init__(self):
        self.size = 769
        self.buckets = [[] for _ in range(self.size)]

    def _hash(self, key):
        return key % self.size

    def add(self, key: int) -> None:
        idx = self._hash(key)
        if key not in self.buckets[idx]:
            self.buckets[idx].append(key)

    def contains(self, key: int) -> bool:
        idx = self._hash(key)
        return key in self.buckets[idx]

    def remove(self, key: int) -> None:
        idx = self._hash(key)
        if key in self.buckets[idx]:
            self.buckets[idx].remove(key)