mirror of
https://github.com/heqin-zhu/algorithm.git
synced 2024-03-22 13:30:46 +08:00
116 lines
3.5 KiB
Python
116 lines
3.5 KiB
Python
''' mbinary
|
|
#########################################################################
|
|
# File : hashTable.py
|
|
# Author: mbinary
|
|
# Mail: zhuheqin1@gmail.com
|
|
# Blog: https://mbinary.coding.me
|
|
# Github: https://github.com/mbinary
|
|
# Created Time: 2018-07-08 16:39
|
|
# Description:
|
|
#########################################################################
|
|
'''
|
|
|
|
class item:
|
|
def __init__(self,key,val,nextItem=None):
|
|
self.key = key
|
|
self.val = val
|
|
self.next = nextItem
|
|
def to(self,it):
|
|
self.next = it
|
|
def __eq__(self,it):
|
|
'''using keyword <in> '''
|
|
return self.key == it.key
|
|
def __bool__(self):
|
|
return self.key is not None
|
|
def __str__(self):
|
|
li = []
|
|
nd = self
|
|
while nd:
|
|
li.append(f'({nd.key}:{nd.val})')
|
|
nd = nd.next
|
|
return ' -> '.join(li)
|
|
def __repr__(self):
|
|
return f'item({self.key},{self.val})'
|
|
class hashTable:
|
|
def __init__(self,size=100):
|
|
self.size = size
|
|
self.slots=[item(None,None) for i in range(self.size)]
|
|
def __setitem__(self,key,val):
|
|
nd = self.slots[self.myhash(key)]
|
|
while nd.next:
|
|
if nd.key ==key:
|
|
if nd.val!=val: nd.val=val
|
|
return
|
|
nd = nd.next
|
|
nd.next = item(key,val)
|
|
|
|
def myhash(self,key):
|
|
if isinstance(key,str):
|
|
key = sum(ord(i) for i in key)
|
|
if not isinstance(key,int):
|
|
key = hash(key)
|
|
return key % self.size
|
|
def __iter__(self):
|
|
'''when using keyword <in>, such as ' if key in dic',
|
|
the dic's __iter__ method will be called,(if hasn't, calls __getitem__
|
|
then ~iterate~ dic's keys to compare whether one equls to the key
|
|
'''
|
|
for nd in self.slots:
|
|
nd = nd.next
|
|
while nd :
|
|
yield nd.key
|
|
nd = nd.next
|
|
def __getitem__(self,key):
|
|
nd =self.slots[ self.myhash(key)].next
|
|
while nd:
|
|
if nd.key==key:
|
|
return nd.val
|
|
nd = nd.next
|
|
raise Exception(f'[KeyError]: {self.__class__.__name__} has no key {key}')
|
|
|
|
def __delitem__(self,key):
|
|
'''note that None item and item(None,None) differ with each other,
|
|
which means you should take care of them and correctly cop with None item
|
|
especially when deleting items
|
|
'''
|
|
n = self.myhash(key)
|
|
nd = self.slots[n].next
|
|
if nd.key == key:
|
|
if nd.next is None:
|
|
self.slots[n] = item(None,None) # be careful
|
|
else:self.slots[n] = nd.next
|
|
return
|
|
while nd:
|
|
if nd.next is None: break # necessary
|
|
if nd.next.key ==key:
|
|
nd.next = nd.next.next
|
|
nd = nd.next
|
|
def __str__(self):
|
|
li = ['\n\n'+'-'*5+'hashTable'+'-'*5]
|
|
for i,nd in enumerate(self.slots):
|
|
li.append(f'{i}: '+str(nd.next))
|
|
return '\n'.join(li)
|
|
|
|
|
|
if __name__ =='__main__':
|
|
from random import randint
|
|
dic = hashTable(16)
|
|
n = 100
|
|
li = [1,2,5,40,324,123,6,22,18,34,50]
|
|
print(f'build hashTable using {li}')
|
|
for i in li:
|
|
dic[i] = '$'+str(i)
|
|
print(dic)
|
|
for i in [1,34,45,123]:
|
|
if i in dic:
|
|
print(f'{i} in dic, deleting it')
|
|
del dic[i]
|
|
else:
|
|
print(f'{i} not in dic, ignore it')
|
|
print(dic)
|
|
print(f'dic[2] is {dic[2]}')
|
|
try:
|
|
dic[-1]
|
|
except Exception as e:
|
|
print(e)
|