|
| 1 | +""" |
| 2 | +LeetCode Problem: Design HashSet |
| 3 | +-------------------------------- |
| 4 | +Design a HashSet without using any built-in hash table libraries. |
| 5 | + |
| 6 | +Implement the MyHashSet class: |
| 7 | + |
| 8 | +Methods: |
| 9 | + - add(key): Inserts the value 'key' into the HashSet. |
| 10 | + - contains(key): Returns True if 'key' exists in the HashSet, else False. |
| 11 | + - remove(key): Removes the value 'key' from the HashSet. |
| 12 | + If 'key' does not exist, do nothing. |
| 13 | + |
| 14 | +Example: |
| 15 | + Input: |
| 16 | + ["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"] |
| 17 | + [[], [1], [2], [1], [3], [2], [2], [2], [2]] |
| 18 | + |
| 19 | + Output: |
| 20 | + [null, null, null, true, false, null, true, null, false] |
| 21 | + |
| 22 | + Explanation: |
| 23 | + myHashSet = MyHashSet() |
| 24 | + myHashSet.add(1) # set = [1] |
| 25 | + myHashSet.add(2) # set = [1, 2] |
| 26 | + myHashSet.contains(1) # returns True |
| 27 | + myHashSet.contains(3) # returns False (not found) |
| 28 | + myHashSet.add(2) # set = [1, 2] |
| 29 | + myHashSet.contains(2) # returns True |
| 30 | + myHashSet.remove(2) # set = [1] |
| 31 | + myHashSet.contains(2) # returns False (already removed) |
| 32 | + |
| 33 | +Constraints: |
| 34 | + - 0 <= key <= 1,000,000 |
| 35 | + - At most 10,000 calls will be made to add, remove, and contains. |
| 36 | +""" |
| 37 | + |
| 38 | +# Method 1: |
| 39 | +class MyHashSet: |
| 40 | + |
| 41 | + def __init__(self): |
| 42 | + self.data = [] |
| 43 | + |
| 44 | + def add(self, key: int) -> None: |
| 45 | + if key not in self.data: |
| 46 | + self.data.append(key) |
| 47 | + |
| 48 | + def remove(self, key: int) -> None: |
| 49 | + if key in self.data: |
| 50 | + self.data.remove(key) |
| 51 | + |
| 52 | + def contains(self, key: int) -> bool: |
| 53 | + if key in self.data: |
| 54 | + return True |
| 55 | + else: |
| 56 | + return False |
| 57 | + |
| 58 | +# Method 2: |
| 59 | +class MyHashSet: |
| 60 | + |
| 61 | + def __init__(self): |
| 62 | + self.data = [False]*100001 |
| 63 | + |
| 64 | + def add(self, key: int) -> None: |
| 65 | + self.data[key] = True |
| 66 | + |
| 67 | + def remove(self, key: int) -> None: |
| 68 | + self.data[key] = False |
| 69 | + |
| 70 | + def contains(self, key: int) -> bool: |
| 71 | + return self.data[key] |
| 72 | + |
| 73 | + |
| 74 | +# Method 3: |
| 75 | +class MyHashSet: |
| 76 | + |
| 77 | + def __init__(self): |
| 78 | + self.size = 10000 |
| 79 | + self.table = [[] for _ in range(self.size)] |
| 80 | + |
| 81 | + def calculate_hash_value(self,key: int): |
| 82 | + return key % self.size |
| 83 | + |
| 84 | + def add(self, key: int) -> None: |
| 85 | + hv = self.calculate_hash_value(key) |
| 86 | + if key not in self.table[hv]: |
| 87 | + self.table[hv].append(key) |
| 88 | + |
| 89 | + def remove(self, key: int) -> None: |
| 90 | + hv = self.calculate_hash_value(key) |
| 91 | + if key in self.table[hv]: |
| 92 | + self.table[hv].remove(key) |
| 93 | + |
| 94 | + def contains(self, key: int) -> bool: |
| 95 | + hv = self.calculate_hash_value(key) |
| 96 | + return key in self.table[hv] |
| 97 | + |
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