50 lines
931 B
Ruby
50 lines
931 B
Ruby
# Work with the Linked List structure,
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# see examples in test/linked_list_test.rb
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module LinkedList
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Node = Struct.new(:value, :next)
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# Reverses a linked list in the iterative case
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def self.reverse(first)
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node = first
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prev = nil
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while node
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second = node.next
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node.next = prev
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prev = node
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node = second
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end
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prev
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end
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# Deletes duplicates from the list using a hash map, runs in O(n) time
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def self.delete_dups(node)
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map = {}
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prev = nil
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while node
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if map[node.value]
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prev.next = node.next
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else
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map[node.value] = true
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prev = node
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end
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node = node.next
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end
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end
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# Detects if the linked list has a loop
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def self.has_loop?(head)
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slow = head
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fast = head
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while fast && fast.next
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slow = slow.next
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fast = fast.next.next
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return true if slow == fast
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end
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return false
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end
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end
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