76 lines
2.1 KiB
Python
76 lines
2.1 KiB
Python
from collections.abc import Callable
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from utils.algo_context import AlgoContext
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from utils.algo_array import Array
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from utils.algo_int import Int
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from utils.algo_range import irange
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UNUSED_MARK = "UNUSED"
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DELETED_MARK = "DELETED"
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class HashTableOpenAddressing:
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"""
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Hashtabelle mit offener Adressierung.
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f – Sondierungsfunktion f(x: Int, i: Int, m: Int) -> Int
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Liefert die Tabellenposition für Schlüssel x beim i-ten Versuch.
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"""
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def __init__(self, m: int, f: Callable[[Int, Int, Int], Int], ctx: AlgoContext):
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self.ctx = ctx
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self.m = Int(m, ctx)
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self.f = f
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self.table = Array([UNUSED_MARK] * m, ctx)
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def insert(self, x: Int) -> bool:
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i = Int(0, self.ctx)
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while i < self.m:
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j = self.f(x, i, self.m)
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if self.is_free(j):
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self.table[j] = x
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return True
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i += 1
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return False
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def search(self, x: Int) -> bool:
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i = Int(0, self.ctx)
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while i < self.m:
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j = self.f(x, i, self.m)
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if self.is_unused(j):
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return False
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if self.table[j] == x:
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return True
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i += 1
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return False
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def delete(self, x: Int) -> bool:
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i = Int(0, self.ctx)
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while i < self.m:
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j = self.f(x, i, self.m)
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if self.is_unused(j):
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return False
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if self.table[j] == x:
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self.table[j].set(DELETED_MARK) # Tombstone setzen (1 write)
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return True
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i += 1
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return False
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def __str__(self):
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return str(self.table)
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def alpha(self) -> float:
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"""Belegungsfaktor der Tabelle."""
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used = sum(0 if self.is_free(Int(i, self.ctx)) else 1
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for i in range(int(self.m)))
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return used / int(self.m)
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def is_unused(self, i: Int) -> bool:
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return self.table[i].value == UNUSED_MARK
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def is_deleted(self, i: Int) -> bool:
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return self.table[i].value == DELETED_MARK
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def is_free(self, i: Int) -> bool:
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return self.is_unused(i) or self.is_deleted(i)
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