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# initialise linked list structure
global LinkedList
# creating empty data and joining pointers
LinkedList = [[-1, i + 1] for i in range(0, 20)]
# set last element to be null pointer
LinkedList[-1][1] = -1
global FirstEmpty
global FirstNode
FirstEmpty = 0
FirstNode = -1
def InsertData():
global FirstEmpty, FirstNode, LinkedList
for i in range(5):
number = int(input("your positive integer number: "))
while number < 0:
print("invalid, must be positive!")
number = int(input("your positive integer number: "))
if FirstEmpty != -1:
# the linked list is not full
NextEmpty = LinkedList[FirstEmpty][1]
LinkedList[FirstEmpty][0] = number
LinkedList[FirstEmpty][1] = FirstNode
FirstNode = FirstEmpty
FirstEmpty = NextEmpty
else:
return
def OutputLinkedList():
global FirstNode, LinkedList
# assign initial node location
next_node = FirstNode
while next_node != -1:
# outputs the data at the given position
print(LinkedList[next_node][0])
# updates the next following pointer
next_node = LinkedList[next_node][1]
InsertData()
OutputLinkedList()
def RemoveData(target_data):
global FirstNode, FirstEmpty, LinkedList
current_node = FirstNode
next_node = LinkedList[FirstNode][1]
if LinkedList[current_node][0] == target_data:
# the first node needs to be removed
new_first_node = LinkedList[current_node][1]
LinkedList[current_node][1] = FirstEmpty
FirstEmpty = current_node
FirstNode = new_first_node
return
while current_node != -1:
# checks if the immediately succeeding element is target
if LinkedList[next_node][0] == target_data:
if LinkedList[next_node][1] == -1:
# the target is at the end of the list
# terminating linked list with null pointer
LinkedList[current_node][1] = -1
# put element in empty list
else:
# the target is in the middle of the list
# skip the removed element
LinkedList[current_node][1] = LinkedList[next_node][1]
LinkedList[next_node][1] = FirstEmpty
FirstEmpty = next_node
return # returning here because only matching for one occurrence
current_node = next_node
next_node = LinkedList[next_node][1]
RemoveData(5)
print("After")
OutputLinkedList()
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