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https://github.com/oddluck/limnoria-plugins.git
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5e74a4a10e
git-subtree-dir: WordGames git-subtree-mainline: a8c0694be8909bdc34ab3f23579b911545b94df6 git-subtree-split: 854e77a6d4d576aad9da8aa9852a1939e205fc4e
109 lines
3.2 KiB
Python
109 lines
3.2 KiB
Python
#!/usr/bin/env python
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"""
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Quick & dirty prefix tree (aka trie).
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"""
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# This got a little uglier because using a nice object-oriented approach took
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# too much time and memory on big trees. Now every node is simply a dict,
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# with the special '*' field meaning that the word is complete at that node.
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class Trie(object):
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def __init__(self):
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self.contents = {'*': False}
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def add(self, value, contents=None):
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if contents is None:
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contents = self.contents
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if not value:
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contents['*'] = True
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return
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prefix = value[0]
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remainder = value[1:]
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child_contents = contents.get(prefix, None)
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if not child_contents:
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child_contents = {'*': False}
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contents[prefix] = child_contents
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self.add(remainder, child_contents)
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def find(self, value):
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"Return true if the value appears, false otherwise."
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x = self.find_prefix(value)
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return x and x['*'] == True
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def find_prefix(self, value, contents=None):
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"Return true if the given prefix appears in the tree."
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if contents is None:
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contents = self.contents
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if not value:
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return contents
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child_contents = contents.get(value[0], None)
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if not child_contents:
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return None
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return self.find_prefix(value[1:], child_contents)
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def dump(self, indent=0, contents=None):
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"Dump the trie to stdout."
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if contents is None:
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contents = self.contents
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for key in sorted(contents.keys()):
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if key == '*':
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continue
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text = indent * ' '
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text += key
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child_contents = contents[key]
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if child_contents['*']:
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text += '*'
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print(text)
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self.dump(indent+2, child_contents)
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if __name__ == '__main__':
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import resource
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import sys
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import time
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if '--perf' in sys.argv:
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# Performance test, last arg should be input file
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start = time.time()
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t = Trie()
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f = open(sys.argv[-1], 'r')
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for line in f:
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t.add(line.strip())
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mem = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
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elapsed = time.time() - start
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print(('Trie created in %g seconds.' % elapsed))
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print(('Used %dMB RAM.' % (mem/1024)))
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else:
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# Regular sanity test
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t = Trie()
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t.add('hell')
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t.add('hello')
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t.add('he')
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t.add('world')
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t.add('alphabet')
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t.add('foo')
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t.add('food')
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t.add('foodie')
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t.add('bar')
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t.add('alphanumeric')
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t.dump()
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assert not t.find('h')
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assert t.find('he')
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assert not t.find('hel')
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assert t.find('hell')
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assert t.find('hello')
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assert not t.find('r')
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assert t.find('world')
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assert not t.find('ba')
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assert t.find('bar')
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assert t.find('alphabet')
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assert t.find('alphanumeric')
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assert not t.find('alpha')
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assert not t.find('f')
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assert not t.find('fo')
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assert t.find('foo')
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assert t.find('food')
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assert not t.find('foodi')
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assert t.find('foodie')
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