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