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Hash Table with Python
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class HashNode: | |
def __init__(self, key, value): | |
self.next = None | |
self.key = key | |
self.value = value | |
class HashTable: | |
def __init__(self): | |
self.table = [None] * 101 | |
def hash(self, key): | |
# Generate hash from key. | |
# Time O(N), Space O(1), where N is the length of key. | |
hashed = 0 | |
for i in range(len(key)): | |
hashed = (256 * hashed + ord(key[i])) % 101 | |
return hashed | |
def add(self, key, value): | |
# Add key, value. | |
# Time O(1), Space O(1), where N is the num of elements in hashtable. | |
bucket = self.hash(key) | |
if not self.table[bucket]: | |
self.table[bucket] = HashNode(key, value) | |
else: | |
temp = self.table[bucket] | |
while temp.next: | |
temp = temp.next | |
temp.next = HashNode(key, value) | |
def find(self, key): | |
# Find value from key. | |
# Time O(1), Space O(1), where N is the num of elements in hashtable. | |
bucket = self.hash(key) | |
if not self.table[bucket]: | |
return False | |
else: | |
temp = self.table[bucket] | |
while temp: | |
if temp.key == key: | |
return temp.value | |
temp = temp.next | |
return False | |
def delete(self, key): | |
# Delete key, value. | |
# Time O(1), Space O(1), where N is the num of elements in hashtable. | |
bucket = self.hash(key) | |
if not self.table[bucket]: | |
return False | |
else: | |
if self.table[bucket].key == key: | |
self.table[bucket] = None | |
else: | |
temp = self.table[bucket] | |
while temp: | |
if temp.next.key == key: | |
temp.next = temp.next.next | |
return | |
temp = temp.next | |
return False |
What happens when all of the cells are filled and then you continue adding elements to the linked list. This gives no advantage. Your HashTable should grow in size given your load factors reaches a limit.
When the hash table is full, you usually transfer the content to a bigger hash table. So maybe a function like a isFull() would help here...therefore dynamically creating a new hash table with a larger space (something like self.table *2).
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What happens when all of the cells are filled and then you continue adding elements to the linked list. This gives no advantage. Your HashTable should grow in size given your load factors reaches a limit.