Created
November 14, 2017 21:17
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Reverse a linked list with mutation
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| # This linked list reversal does not involve a stack, it simply | |
| #creates a new set of nodes that point the opposite direction. | |
| class LinkedListNode | |
| attr_accessor :value, :next_node | |
| def initialize(value, next_node=nil) | |
| @value = value | |
| @next_node = next_node | |
| end | |
| end | |
| def reverse_list(node, previous=nil) | |
| return if node.nil? | |
| @head = LinkedListNode.new(node.value, previous) | |
| reverse_list(node.next_node, @head) | |
| return @head | |
| end | |
| def print_values(node) | |
| print "#{node.value} --> " | |
| if node.next_node.nil? | |
| print "nil\n" | |
| return | |
| else | |
| print_values(node.next_node) | |
| end | |
| end | |
| node1 = LinkedListNode.new(37) | |
| node2 = LinkedListNode.new(99, node1) | |
| node3 = LinkedListNode.new(12, node2) | |
| print_values(node3) | |
| puts "---------" | |
| revlist = reverse_list(node3) | |
| print_values(revlist) |
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