DataStructuresAndAlgorithms/Codes/Practical-A1.py

'''
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.

Code from Data Structures and Algorithms (SPPU - Second Year - Computer Engineering - Content) repository on KSKA Git: https://git.kska.io/sppu-se-comp-content/DataStructuresAndAlgorithms/
'''

# BEGINNING OF CODE
class HashEntry:
# Blueprint for entry in hash table
    def __init__(self):
    # Initializing empty values
        self.name = None
        self.num = -1

    def insert(self, name, num):
    # Insert value
        self.name = name
        self.num = num

    def collision(self):
    # Handle collision
        return self.name is not None

def hashOne(size, val):
# Calculate first hashing function
    return val % size

def hashTwo(val):
# Calculate second hashing function
    return 7 - (val % 7)

def finalHash(val, size, i):
# Determine final position of value in hash table (after first and second hash is caluclated)
    return (hashOne(size, val) + i * hashTwo(val)) % size

def stringToInt(strn):
# ASCII value of each character
    sum = 0
    for i in strn:
        sum += ord(i)
    return sum

class LinearProbing:
# Function to handle linear probing
    def __init__(self, size):
        self.size = size
        self.HashTable = []
        for _ in range(size):
            self.HashTable.append(HashEntry())

    def insert(self):
        inputStr = input("Enter telephone NUMBER and NAME of client (separated by space):\t")
        inputVal = inputStr.split()

        if len(inputVal) != 2:
            print("\n==========\nPlease enter both telephone number and name.\n==========")
            return

        num, name = inputVal
        name2 = stringToInt(name)
        pos = hashOne(self.size, name2)

        i = 1
        while self.HashTable[pos].collision():
            pos = (pos + i) % self.size
            i += 1
        self.HashTable[pos].insert(name, num)
        print("\n==========\nInserted\n==========")

    def search(self):
        name = input("Enter name of the client:\t")
        name2 = stringToInt(name)
        pos = hashOne(self.size, name2)

        i = 1
        while self.HashTable[pos].name != name:
            pos = (pos + i) % self.size
            i += 1
            if i == self.size + 1:
                break
        else:
            print("\n==========\nTelephone number of the client", name, "is", self.HashTable[pos].num, "\n==========")
            return
        print("\n==========\nClient not found.\n==========")

    def display(self):
        j = 0
        print("Pos", "Name", "Value", sep="\t|\t")
        print("-----", "-----", "-----", sep="\t+\t")
        for i in self.HashTable:
            print(j, i.name, i.num, sep="\t|\t")
            j += 1

class DoubleHashing:
# Function to handle double hashing
    def __init__(self, size):
        self.size = size
        self.HashTable = []
        for _ in range(size):
            self.HashTable.append(HashEntry())

    def insert(self):
        inputStr = input("Enter telephone NUMBER and NAME of client (separated by space):\t")
        inputVal = inputStr.split()

        if len(inputVal) != 2:
            print("\n==========\nPlease enter both telephone number and name.\n==========")
            return

        num, name = inputVal
        name2 = stringToInt(name)

        i = 0
        while True:
            pos = finalHash(name2, self.size, i)
            if self.HashTable[pos].collision():
                i += 1
            else:
                break
        self.HashTable[pos].insert(name, num)
        print("\n==========\nInserted\n==========")

    def search(self):
        name = input("Enter name of the client:\t")
        name2 = stringToInt(name)
        i = 0
        while True:
            pos = finalHash(name2, self.size, i)
            if self.HashTable[pos].name != name:
                i += 1
            else:
                break
            if i == self.size:
                break
        print("\n==========\nTelephone number of client", name, "is", self.HashTable[pos].num, "\n==========")

    def display(self):
        j = 0
        print("Pos", "Name", "Value", sep="\t|\t")
        print("-----", "-----", "-----", sep="\t+\t")
        for i in self.HashTable:
            print(j, i.name, i.num, sep="\t|\t")
            j += 1

def main():
# Main function with options
    tableSize = int(input("Enter size of hash table:\t"))
    method = None

    while True:
        print("----- MAIN MENU -----")
        print("1 -> Linear Probing")
        print("2 -> Double Hashing")
        print("3 -> Exit")
        optn = int(input("Choose an option (1-3):\t"))
        if optn == 1:
            method = LinearProbing(tableSize)
        elif optn == 2:
            method = DoubleHashing(tableSize)
        elif optn == 3:
            print("\n\n## END OF CODE\n")
            exit(1)
        else:
            print("Please choose a valid option (1-3).")
            continue
    
        while True:
            print("\n----- CHOOSE OPERATION (HASH TABLE) -----")
            print("1 -> Insert")
            print("2 -> Search")
            print("3 -> Display")
            print("4 -> Return to previous menu")
            optn = int(input("Choose an option (1-4):\t"))
            if optn == 1:
                method.insert()
            elif optn == 2:
                method.search()
            elif optn == 3:
                method.display()
            elif optn == 4:
                break
            else:
                print("Please choose a valid option (1-4).")
                continue

# Calling main function
main()
# END OF CODE