Tutorial 1 - 7 February 2025
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T1/Q1 - moveEvenItemsToBack_LL.py
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102
T1/Q1 - moveEvenItemsToBack_LL.py
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class ListNode:
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def __init__(self, item):
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self.item = item
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self.next = None
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class LinkedList:
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def __init__(self):
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self.size = 0
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self.head = None
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def printList(self):
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cur = self.head
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if not cur:
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print("Empty")
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return
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while cur:
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print(cur.item, end=" ")
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cur = cur.next
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print()
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def removeAllItems(self):
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self.head = None
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self.size = 0
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def findNode(self, index):
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if index < 0 or index >= self.size:
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return None
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cur = self.head
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while index > 0:
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cur = cur.next
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index -= 1
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return cur
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def insertNode(self, index, value):
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if index < 0 or index > self.size:
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return -1
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newNode = ListNode(value)
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if index == 0: # Insert at the beginning
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newNode.next = self.head
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self.head = newNode
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else:
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prev = self.findNode(index - 1)
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newNode.next = prev.next
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prev.next = newNode
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self.size += 1
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return 0
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def removeNode(self, index):
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if index < 0 or index >= self.size:
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return -1
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if index == 0: # Remove the first node
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self.head = self.head.next
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else:
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prev = self.findNode(index - 1)
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prev.next = prev.next.next
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self.size -= 1
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return 0
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def moveEvenItemsToBack(ll):
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if ll.size < 2:
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return
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cur = ll.head
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index = 0
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for _ in range(ll.size):
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if cur.item % 2 == 0:
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even_value = cur.item
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cur = cur.next
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ll.removeNode(index)
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ll.insertNode(ll.size, even_value)
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else:
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cur = cur.next
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index += 1
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if __name__ == "__main__":
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ll = LinkedList()
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while True:
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print("1: Insert an integer to the linked list:")
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print("2: Move all even integers to the back of the linked list:")
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print("0: Quit:")
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choice = int(input("Please input your choice (1/2/0): "))
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if choice == 1:
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value = int(input("Input an integer that you want to add to the linked list: "))
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ll.insertNode(ll.size, value)
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print("The resulting linked list is:")
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ll.printList()
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elif choice == 2:
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moveEvenItemsToBack(ll)
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print("The resulting linked list after moving even integers to the back is:")
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ll.printList()
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elif choice == 0:
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ll.removeAllItems()
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break
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else:
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print("Choice unknown;")
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119
T1/Q2 - moveMaxToFront_LL.py
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119
T1/Q2 - moveMaxToFront_LL.py
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class ListNode:
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def __init__(self, item):
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self.item = item
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self.next = None
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class LinkedList:
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def __init__(self):
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self.size = 0
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self.head = None
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def printList(ll):
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cur = ll.head
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if cur is None:
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print("Empty")
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return
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while cur is not None:
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print(cur.item, end=" ")
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cur = cur.next
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print()
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def findNode(ll, index):
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if ll is None or index < 0 or index >= ll.size:
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return None
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temp = ll.head
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while index > 0:
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temp = temp.next
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if temp is None:
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return None
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index -= 1
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return temp
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def insertNode(ll, index, value):
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if ll is None or index < 0 or index > ll.size:
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return -1
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new_node = ListNode(value)
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if index == 0: # Insert at the beginning
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new_node.next = ll.head
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ll.head = new_node
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else:
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pre = findNode(ll, index - 1)
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if pre is None:
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return -1
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new_node.next = pre.next
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pre.next = new_node
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ll.size += 1
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return 0
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def removeNode(ll, index):
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if ll is None or index < 0 or index >= ll.size:
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return -1
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if index == 0: # Remove the first node
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ll.head = ll.head.next
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else:
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pre = findNode(ll, index - 1)
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if pre is None or pre.next is None:
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return -1
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pre.next = pre.next.next
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ll.size -= 1
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return 0
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def removeAllItems(ll):
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ll.head = None
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ll.size = 0
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def moveMaxToFront(ll):
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if ll.head is None or ll.head.next is None: # Empty list or single node
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return -1
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pre_max = None
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max_node = ll.head
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cur = ll.head
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while cur.next is not None:
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if cur.next.item > max_node.item:
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pre_max = cur
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max_node = cur.next
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cur = cur.next
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if pre_max is None: # Max node is already at the front
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return 0
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# Move the max node to the front
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pre_max.next = max_node.next
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max_node.next = ll.head
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ll.head = max_node
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return 0
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if __name__ == "__main__":
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ll = LinkedList()
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while True:
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print("1: Insert an integer to the linked list:")
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print("2: Move the largest stored value to the front of the list:")
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print("0: Quit:")
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choice = int(input("Please input your choice (1/2/0): "))
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if choice == 1:
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value = int(input("Input an integer that you want to add to the linked list: "))
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insertNode(ll, ll.size, value)
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print("The resulting linked list is:")
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printList(ll)
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elif choice == 2:
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moveMaxToFront(ll)
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print("The resulting linked list after moving the largest stored value to the front of the list is:")
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printList(ll)
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elif choice == 0:
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removeAllItems(ll)
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break
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else:
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print("Choice unknown.")
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123
T1/Q3 - removeDuplicatesSortedLL.py
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123
T1/Q3 - removeDuplicatesSortedLL.py
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class ListNode:
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def __init__(self, item):
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self.item = item
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self.next = None
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class LinkedList:
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def __init__(self):
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self.size = 0
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self.head = None
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# Function to remove duplicates from a sorted linked list
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def remove_duplicates_sorted_ll(ll):
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current = ll.head
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if current is None:
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return
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while current.next is not None:
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if current.item == current.next.item:
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temp = current.next.next
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current.next = temp
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ll.size -= 1
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else:
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current = current.next
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def print_list(ll):
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current = ll.head
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if current is None:
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print("Empty")
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return
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while current is not None:
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print(current.item, end=" ")
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current = current.next
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print()
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def remove_all_items(ll):
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current = ll.head
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while current is not None:
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temp = current.next
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current = None
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current = temp
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ll.head = None
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ll.size = 0
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def find_node(ll, index):
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if ll is None or index < 0 or index >= ll.size:
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return None
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temp = ll.head
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while index > 0:
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temp = temp.next
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if temp is None:
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return None
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index -= 1
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return temp
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def insert_node(ll, index, value):
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if ll is None or index < 0 or index > ll.size:
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return -1
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new_node = ListNode(value)
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# If inserting at the head
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if index == 0:
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new_node.next = ll.head
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ll.head = new_node
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ll.size += 1
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return 0
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# Insert at other positions
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prev_node = find_node(ll, index - 1)
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if prev_node is not None:
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new_node.next = prev_node.next
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prev_node.next = new_node
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ll.size += 1
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return 0
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return -1
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def remove_node(ll, index):
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if ll is None or index < 0 or index >= ll.size:
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return -1
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# Remove head node
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if index == 0:
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ll.head = ll.head.next
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ll.size -= 1
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return 0
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# Remove other nodes
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prev_node = find_node(ll, index - 1)
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if prev_node is not None and prev_node.next is not None:
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prev_node.next = prev_node.next.next
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ll.size -= 1
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return 0
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return -1
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if __name__ == "__main__":
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ll = LinkedList()
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while True:
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print("1: Insert an integer to the linked list:")
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print("2: Remove duplicates from a sorted linked list:")
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print("0: Quit:")
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choice = int(input("Please input your choice(1/2/0): "))
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if choice == 1:
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value = int(input("Input an integer that you want to add to the linked list: "))
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insert_node(ll, ll.size, value)
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print("The resulting linked list is: ")
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print_list(ll)
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elif choice == 2:
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remove_duplicates_sorted_ll(ll)
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print("The resulting linked list after removing duplicate values from the sorted linked list is: ")
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print_list(ll)
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elif choice == 0:
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remove_all_items(ll)
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break
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else:
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print("Choice unknown;")
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