diff --git a/data-structures/linked-lists/circularsinglelinkedlist.py b/data-structures/linked-lists/circularsinglelinkedlist.py new file mode 100644 index 0000000..1ef3c6e --- /dev/null +++ b/data-structures/linked-lists/circularsinglelinkedlist.py @@ -0,0 +1,116 @@ +class Node: + def __init__(self, data): + self.data = data + self.next = None + + +class CircularLinkedList: + def __init__(self): + self.head = None + + def get_node(self, index): + if self.head is None: + return None + current = self.head + for i in range(index): + current = current.next + if current == self.head: + return None + return current + + def get_prev_node(self, ref_node): + if self.head is None: + return None + current = self.head + while current.next != ref_node: + current = current.next + return current + + def insert_after(self, ref_node, new_node): + new_node.next = ref_node.next + ref_node.next = new_node + + def insert_before(self, ref_node, new_node): + prev_node = self.get_prev_node(ref_node) + self.insert_after(prev_node, new_node) + + def insert_at_end(self, new_node): + if self.head is None: + self.head = new_node + new_node.next = new_node + else: + self.insert_before(self.head, new_node) + + def insert_at_beg(self, new_node): + self.insert_at_end(new_node) + self.head = new_node + + def remove(self, node): + if self.head.next == self.head: + self.head = None + else: + prev_node = self.get_prev_node(node) + prev_node.next = node.next + if self.head == node: + self.head = node.next + + def display(self): + if self.head is None: + return + current = self.head + while True: + print(current.data, end = ' ') + current = current.next + if current == self.head: + break + + +a_cllist = CircularLinkedList() + +print('Menu') +print('insert after ') +print('insert before ') +print('insert at beg') +print('insert at end') +print('remove ') +print('quit') + +while True: + print('The list: ', end = '') + a_cllist.display() + print() + do = input('What would you like to do? ').split() + + operation = do[0].strip().lower() + + if operation == 'insert': + data = int(do[1]) + position = do[3].strip().lower() + new_node = Node(data) + suboperation = do[2].strip().lower() + if suboperation == 'at': + if position == 'beg': + a_cllist.insert_at_beg(new_node) + elif position == 'end': + a_cllist.insert_at_end(new_node) + else: + index = int(position) + ref_node = a_cllist.get_node(index) + if ref_node is None: + print('No such index.') + continue + if suboperation == 'after': + a_cllist.insert_after(ref_node, new_node) + elif suboperation == 'before': + a_cllist.insert_before(ref_node, new_node) + + elif operation == 'remove': + index = int(do[1]) + node = a_cllist.get_node(index) + if node is None: + print('No such index.') + continue + a_cllist.remove(node) + + elif operation == 'quit': + break \ No newline at end of file pFad - Phonifier reborn

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