Separate Chaining in Python

Author: Deepali-Srivastava

hashing/separate-chaining.py

@@ -0,0 +1,166 @@
+# Copyright (C) Deepali Srivastava - All Rights Reserved
+# This code is part of DSA course available on CourseGalaxy.com  
+
+##################################################################
+
+class studentRecord:
+    def __init__(self,i,name):
+        self.studentId = i
+        self.studentName = name
+
+    def get_student_id(self):
+        return self.studentId
+
+    def set_student_id(self,i):
+        self.studentId = i
+        
+    def __str__(self):
+        return str(self.studentId) + " "  + self.studentName 
+
+##################################################################
+    
+class Node:
+    def __init__(self,value):
+        self.info = value 
+        self.link = None 
+        
+##################################################################
+
+class SingleLinkedList:
+    def __init__(self):
+        self.start = None
+
+    def display_list(self):
+        if self.start is None:
+            print("___")
+            return
+        p = self.start 
+        while p is not None:
+            print(p.info , " ", end='')
+            p = p.link 
+        print()
+    
+    def search(self,x):
+        p = self.start
+        while p is not None:
+            if p.info.get_student_id() == x:
+                return p.info
+            p = p.link
+        else:
+            return None
+
+    def insert_in_beginning(self, data):
+        temp = Node(data)
+        temp.link = self.start
+        self.start = temp
+    
+    def delete_node(self,x):
+        if self.start is None:
+            print("List is empty") 
+            return 
+
+        # Deletion of first node
+        if self.start.info.get_student_id() == x:
+            self.start = self.start.link   
+            return 
+
+        # Deletion in between or at the end
+        p = self.start 
+        while p.link is not None:
+            if p.link.info.get_student_id() == x:
+                break 	
+            p = p.link 
+
+        if p.link is None:
+            print("Element ", x ,"not in list") 
+        else:
+            p.link = p.link.link
+            
+##################################################################
+   
+
+class HashTable:
+
+    def __init__(self,tableSize):
+        self.m = tableSize   
+        self.array = [None] * self.m
+        self.n = 0  
+
+    def hash(self, key):
+        return (key % self.m)
+
+    def display_table(self):
+        for i in range(self.m):
+            print( "[" , i , "]  -->  ", end ='' )
+            if self.array[i]!= None:
+                self.array[i].display_list()
+            else:
+               print("___")
+        
+    
+    def search(self, key):
+        h = self.hash(key)
+        if self.array[h] != None:
+            return self.array[h].search(key)
+        return None        
+               
+    def insert(self, newRecord):
+        key = newRecord.get_student_id()
+        h = self.hash(key)
+
+        if self.array[h] == None:
+            self.array[h] = SingleLinkedList()
+        self.array[h].insert_in_beginning(newRecord)
+        self.n+=1
+    
+   
+   
+    def delete(self, key):
+        h = self.hash(key)
+        if self.array[h] != None:
+            self.array[h].delete_node(key)
+            self.n-=1
+        else:
+            print("Value " , key , " not present")
+
+    
+                
+##################################################################
+               
+size = int(input("Enter size of table : "))
+table = HashTable(size)
+
+while True:
+    print("1.Insert a record")
+    print("2.Search a record")
+    print("3.Delete a record")
+    print("4.Display table")
+    print("5.Exit")
+
+    choice = int(input("Enter your choice : "))
+    if choice == 1:
+        id = int(input("Enter student id : "))
+        name = input("Enter student name : ")
+        aRecord = studentRecord(id,name)
+        table.insert(aRecord)
+    elif choice == 2:
+        id = int(input("Enter a key to be searched : "))
+        aRecord = table.search(id)
+        if  aRecord is None:
+            print("Key not found")
+        else:
+            print(aRecord)
+    elif choice == 3:
+          id = int(input("Enter a key to be deleted :"))
+          table.delete(id)
+    elif choice == 4:
+          table.display_table()
+    elif choice == 5:
+          break
+    else:
+          print("Wrong option") 
+    print() 
+
+        
+
+