design hashset

0816_design-hashset/README.md

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+Design a HashSet without using any built-in hash table libraries.
+
+Implement `MyHashSet` class:
+
+*   `void add(key)` Inserts the value `key` into the HashSet.
+*   `bool contains(key)` Returns whether the value `key` exists in the HashSet or not.
+*   `void remove(key)` Removes the value `key` in the HashSet. If `key` does not exist in the HashSet, do nothing.
+
+**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)
+
+**Constraints:**
+
+*   `0 <= key <= 106`
+*   At most `104` calls will be made to `add`, `remove`, and `contains`.

0816_design-hashset/python3/solution.py

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+from collections import deque
+
+class MyHashSet:
+
+    def __init__(self):
+        self.hashDivisor = 769 # Pick a prime number to avoid collisions
+        self.buckets = [Bucket() for _ in range(self.hashDivisor)]
+        
+
+    def add(self, key: int) -> None:
+        hash = self.hash(key)
+        self.buckets[hash].add(key)
+
+    def remove(self, key: int) -> None:
+        hash = self.hash(key)
+        self.buckets[hash].remove(key)
+
+    def contains(self, key: int) -> bool:
+        hash = self.hash(key)
+        return self.buckets[hash].contains(key)
+        
+    def hash(self, key: int) -> int:
+        return key % self.hashDivisor
+
+class Bucket:
+    def __init__(self):
+        self.d = deque()
+        pass
+    
+    def add(self, key: int) -> None:
+        if key not in self.d:
+            self.d.append(key)
+    
+    def remove(self, key: int) -> None:
+        try:
+            self.d.remove(key)
+        except:
+            pass
+        
+    def contains(self, key: int) -> None:
+        return key in self.d
+    
+    
+# Your MyHashSet object will be instantiated and called as such:
+# obj = MyHashSet()
+# obj.add(key)
+# obj.remove(key)
+# param_3 = obj.contains(key)