last lab

labPython/lab17/task_1.py

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+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.prev = None
+        self.next = None
+
+
+def create_list(arr):
+    if not arr:
+        return None
+    head = Node(arr[0])
+    cur = head
+    for x in arr[1:]:
+        n = Node(x)
+        cur.next = n
+        n.prev = cur
+        cur = n
+    return head
+
+
+def print_list(head):
+    res = []
+    while head:
+        res.append(str(head.data))
+        head = head.next
+    print("Список:", " ".join(res) if res else "null")
+
+
+def remove_odd_positions(head):
+    index = 1
+    cur = head
+    new_head = None
+    last = None
+    while cur:
+        nxt = cur.next
+        if index % 2 == 0:
+            if not new_head:
+                new_head = cur
+                cur.prev = None
+            else:
+                last.next = cur
+                cur.prev = last
+            last = cur
+        index += 1
+        cur = nxt
+    if last:
+        last.next = None
+    return new_head
+
+
+while True:
+    try:
+        print("\n1 - Ввести список\n0 - Выход")
+        cmd = input("Выбор: ")
+        if cmd == "0":
+            break
+        if cmd == "1":
+            arr = list(map(int, input("Введите числа: ").split()))
+            head = create_list(arr)
+            head = remove_odd_positions(head)
+            print_list(head)
+    except:
+        print("Ошибка ввода")