205 lines
6.3 KiB
Python
205 lines
6.3 KiB
Python
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"""
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THIS CODE HAS BEEN TESTED AND IS FULLY OPERATIONAL.
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Problem Statement: Consider telephone book database of N clients. Make use of a hash table implementation to quickly look up client's telephone number. Make use of two collision handling techniques and compare them using number of comparisons required to find a set of telephone numbers.
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Code from DataStructuresAndAlgorithms (SPPU - Second Year - Computer Engineering - Content) repository on KSKA Git: https://git.kska.io/sppu-se-comp-content/DataStructuresAndAlgorithms/
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"""
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# BEGINNING OF CODE
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class HashTable1:
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"""linear Probing without replacement"""
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def __init__(self, size: int) -> None:
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self.record = []
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self.m = size
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for _ in range(size):
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self.record.append([0, ""])
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def display_table(self) -> None:
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print("Hash table using linear probing (without replacement):\t")
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for i in range(len(self.record)):
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print(i, self.record[i])
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def hash_function(self, tel: int) -> int:
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key = (tel % self.m)
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return key
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def generate_table(self, recs: list[list]) -> None:
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for rec in recs:
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self.insert_rec(rec)
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def insert_rec(self, rec: list) -> None:
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key = self.hash_function(rec[0])
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if (self.record[key][0] == 0):
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self.record[key][0] = rec[0]
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self.record[key][1] = rec[1]
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else:
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while (self.record[key][0] != 0):
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key = ((key+1) % self.m)
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self.record[key][0] = rec[0]
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self.record[key][1] = rec[1]
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class HashTable2:
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"""linear Probing with replacement"""
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def __init__(self, size: int) -> None:
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self.record = []
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self.m = size
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for _ in range(size):
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self.record.append([0, "", -1])
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def display_table(self) -> None:
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print("Hash table using linear probing (with replacement):\t")
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for i in range(len(self.record)):
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print(i, self.record[i])
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def hash_function(self, tel: int) -> int:
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key = (tel % self.m)
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return key
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def generate_table(self, recs: list[list]) -> None:
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for rec in recs:
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self.insert_rec(rec)
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def insert_rec(self, rec: list) -> None:
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key = self.hash_function(rec[0])
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if (self.record[key][0] == 0):
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self.record[key][0] = rec[0]
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self.record[key][1] = rec[1]
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self.record[key][2] = -1
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else:
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if (self.hash_function(self.record[key][0]) == key):
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last_elmt = key
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while (self.record[last_elmt][2] != -1):
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last_elmt = self.record[last_elmt][2]
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k = last_elmt
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while (self.record[k][0] != 0):
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k = ((k+1) % self.m)
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self.record[last_elmt][2] = k
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self.record[k][0] = rec[0]
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self.record[k][1] = rec[1]
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self.record[k][2] = -1
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else:
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for i in range(self.m):
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if (self.record[i][2] == key):
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prev_link_key = i
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old_rec_tel = self.record[key][0]
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old_rec_name = self.record[key][1]
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old_rec_link = self.record[key][2]
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self.record[key][0] = rec[0]
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self.record[key][1] = rec[1]
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self.record[key][2] = -1
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k = key
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while (self.record[k][0] != 0):
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k = ((k+1) % self.m)
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self.record[prev_link_key][2] = k
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self.record[k][0] = old_rec_tel
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self.record[k][1] = old_rec_name
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self.record[k][2] = old_rec_link
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class HashTable3:
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"""Double hashing"""
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def __init__(self, size: int) -> None:
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self.record = []
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self.m = size
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for _ in range(size):
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self.record.append([0, ""])
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if (size <= 3):
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self.prime = size
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else:
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prime = [2, 3]
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for i in range(size):
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for j in prime:
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if (i % j == 0):
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p = False
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break
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if (p):
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prime.append(i)
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self.prime = prime[-1]
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def hash1(self, key: int) -> int:
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return (key % self.m)
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def hash2(self, key: int) -> int:
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return (self.prime - (key % self.prime))
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def display_table(self) -> None:
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print("Hash table using double hashing:\t")
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for i in range(len(self.record)):
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print(i, self.record[i])
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def generate_table(self, recs: list[list]) -> None:
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for rec in recs:
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self.insert_rec(rec)
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def insert_rec(self, rec: list) -> None:
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i = 0
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key = self.hash1(rec[0])
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k2 = (key + i*self.hash2(rec[0])) % self.m
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while (self.record[k2][0] != 0):
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k2 = (key + i*self.hash2(rec[0])) % self.m
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i += 1
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self.record[k2][0] = rec[0]
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self.record[k2][1] = rec[1]
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def input_records(n: int) -> list[list]:
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records = []
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for i in range(n):
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print(f"--- PERSON {i+1} ---")
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name = input("Name of the person:\t")
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tel = int(input("Telephone number:\t"))
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records.append([tel, name])
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print("--- DETAILS SAVED ---")
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return records
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n = int(input("Total number of records are:\t"))
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records = input_records(n)
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ch = 1
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while(ch != 5):
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print("--- MAIN MENU")
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print("1 -> Enter records")
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print("2 -> Use linear Probing (without replacement)")
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print("3 -> Use linear Probing (with replacement)")
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print("4 -> Use double hashing")
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print("5 -> Exit")
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ch = int(input("Choose an option (1-5):\t"))
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match (ch):
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case 1:
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n = int(input("Total number of records:\t"))
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records = input_records(n)
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case 2:
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t1 = HashTable1(n)
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t1.generate_table(records)
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t1.display_table()
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case 3:
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t2 = HashTable2(n)
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t2.generate_table(records)
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t2.display_table()
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case 4:
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t3 = HashTable3(n)
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t3.generate_table(records)
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t3.display_table()
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case 5:
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print("\n## END OF CODE\n")
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case default:
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print("Please choose a valid option (1-5).")
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# END OF CODE
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