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hello-algo/en/codes/python/chapter_hashing/array_hash_map.py

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"""
File: array_hash_map.py
Created Time: 2022-12-14
Author: msk397 (machangxinq@gmail.com)
"""
class Pair:
"""Key-value pair"""
def __init__(self, key: int, val: str):
self.key = key
self.val = val
class ArrayHashMap:
"""Hash table based on array implementation"""
def __init__(self):
"""Constructor"""
# Initialize an array, containing 100 buckets
self.buckets: list[Pair | None] = [None] * 100
def hash_func(self, key: int) -> int:
"""Hash function"""
index = key % 100
return index
def get(self, key: int) -> str:
"""Query operation"""
index: int = self.hash_func(key)
pair: Pair = self.buckets[index]
if pair is None:
return None
return pair.val
def put(self, key: int, val: str):
"""Add operation"""
pair = Pair(key, val)
index: int = self.hash_func(key)
self.buckets[index] = pair
def remove(self, key: int):
"""Remove operation"""
index: int = self.hash_func(key)
# Set to None, representing removal
self.buckets[index] = None
def entry_set(self) -> list[Pair]:
"""Get all key-value pairs"""
result: list[Pair] = []
for pair in self.buckets:
if pair is not None:
result.append(pair)
return result
def key_set(self) -> list[int]:
"""Get all keys"""
result = []
for pair in self.buckets:
if pair is not None:
result.append(pair.key)
return result
def value_set(self) -> list[str]:
"""Get all values"""
result = []
for pair in self.buckets:
if pair is not None:
result.append(pair.val)
return result
def print(self):
"""Print hash table"""
for pair in self.buckets:
if pair is not None:
print(pair.key, "->", pair.val)
"""Driver Code"""
if __name__ == "__main__":
# Initialize hash table
hmap = ArrayHashMap()
# Add operation
# Add key-value pair (key, value) to the hash table
hmap.put(12836, "Ha")
hmap.put(15937, "Luo")
hmap.put(16750, "Suan")
hmap.put(13276, "Fa")
hmap.put(10583, "Ya")
print("\nAfter adding, the hash table is\nKey -> Value")
hmap.print()
# Query operation
# Enter key to the hash table, get value
name = hmap.get(15937)
print("\nEnter student ID 15937, found name " + name)
# Remove operation
# Remove key-value pair (key, value) from the hash table
hmap.remove(10583)
print("\nAfter removing 10583, the hash table is\nKey -> Value")
hmap.print()
# Traverse hash table
print("\nTraverse key-value pairs Key->Value")
for pair in hmap.entry_set():
print(pair.key, "->", pair.val)
print("\nIndividually traverse keys Key")
for key in hmap.key_set():
print(key)
print("\nIndividually traverse values Value")
for val in hmap.value_set():
print(val)