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  1. class Node:
  2.     def __init__(self, value, next=None):
  3.         self.value = value
  4.         self.next = next
  5.  
  6. # For testing
  7. def print_linked_list(head):
  8.     current = head
  9.     while current:
  10.         print(current.value, end=" -> " if current.next else "\n")
  11.         current = current.next
  12.  
  13. def find_max(head):
  14.     maxv = head.value
  15.     cur = head.next
  16.     while (cur):
  17.     	maxv = max(maxv, cur.value)
  18.     	cur = cur.next
  19.     return maxv
  20.  
  21. def remove_tail(head):
  22.     if head is None:
  23.         return None
  24.     if head.next is None:
  25.         return None 
  26.  
  27.     current = head
  28.     while current.next.next: 
  29.         current = current.next
  30.  
  31.     current.next = None
  32.     return head
  33.  
  34. def delete_dupes(head):
  35. 	temph = Node(0,head)
  36. 	prev = temph
  37. 	cur = head
  38. 	cur2 = head.next
  39. 	while (cur2):
  40. 		if (cur.value == cur2.value):
  41. 			prev.next = cur2.next
  42. 			cur = cur2.next
  43. 			cur2 = cur.next
  44. 		else:
  45. 			prev = cur
  46. 			cur = cur2
  47. 			cur2 = cur2.next
  48. 	return temph.next
  49.  
  50.  
  51. class Node:
  52.     def __init__(self, value, next=None):
  53.         self.value = value
  54.         self.next = next
  55.  
  56. def has_cycle(head):
  57.     slow = head
  58.     fast = head.next.next
  59.     while (slow.next and fast):
  60.     	if (slow == fast):
  61.     		return True
  62.     	slow = slow.next
  63.     	fast = fast.next.next
  64.     return False
  65. def remove_nth_from_end(head, n):
  66.     count = 1
  67.     cur = head.next
  68.     while (cur):
  69.     	count+=1
  70.     	cur = cur.next
  71.     temph = Node(0,head)
  72.     prev = temph
  73.     cur = head
  74.     for i in range(count-n):
  75.     	prev = cur
  76.     	cur = cur.next
  77.     prev.next = cur.next
  78.     return temph.next
  79.  
  80. def reverse_first_k(head, k):
  81. 	temph = Node(0,head)
  82. 	prev = temph
  83. 	cur = head
  84.  
  85. 	for i in range(k-1):
  86. 		if (cur == None):
  87. 			break
  88. 		nexte = cur.next
  89. 		prev.next = cur.next
  90. 		prev = cur
  91. 		cur = nexte
  92. 	return temph.next
  93. head = Node("apple", Node("cherry", Node("orange", Node("peach", Node("pear")))))
  94.  
  95. print_linked_list(reverse_first_k(head, 3))
  96.  
Success #stdin #stdout 0.1s 14140KB
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Standard input is empty
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cherry -> orange -> peach -> pear
https://ideone.com/Wkgd7N
language:
Python 3 (python  3.12)
created:
2 days ago
visibility:
public

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