Brendan Chen
59aef7e358
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48 lines
1.4 KiB
Python
48 lines
1.4 KiB
Python
# also called "double hashing"
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class Dictionary:
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backing: "list" = [None] * 100
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def hash(self, key: str):
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ord_total = 0;
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for letter in key:
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ord_total += ord(letter)
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return ord_total % len(self.backing)
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def secondary_hash(self, key: str):
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# never actually use this; this is just a demo
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return len(key) + 1 # ensure never 0
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def get_actual_index(
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self,
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key: str,
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num_attempts = 0,
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):
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# handles repeated hashing
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index = self.hash(key) + num_attempts * self.secondary_hash(key)
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# for retrieving a value:
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# if key at index matches key, we have the correct index
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# otherwise, hash again
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if self.backing[index] is not None and self.backing[index][0] != key:
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return self.get_actual_index(key, num_attempts + 1)
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return index
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def get(self, key: str):
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index = self.get_actual_index(key)
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return self.backing[index][1]
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def set(self, key: str, value):
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index = self.get_actual_index(key)
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# instead of storing just values, store tuples (key-value pairs)
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self.backing[index] = (key, value)
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sample_dict = Dictionary()
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sample_dict.set("test string", "test value")
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sample_dict.set("tets string", "this value will *not* overwrite the other one")
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print(sample_dict.get("test string"))
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print(sample_dict.get("tets string"))
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print(sample_dict.backing)
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