1823

1801-1900/1823_find_the_winner_of_the_circular_game.rb

@@ -0,0 +1,43 @@
+class CircularList
+ class Node
+ attr_accessor :val, :next
+ def initialize(val, next_node = nil)
+ @val = val
+ @next = next_node
+ end
+ end
+
+ attr_reader :head, :tail
+ def initialize(n)
+ @head = CircularList::Node.new(1)
+ curr = @head
+ (2..n).each do |i|
+ curr.next = CircularList::Node.new(i)
+ curr = curr.next
+ end
+ curr.next = @head
+ @tail = curr
+ end
+
+ def remove_each_k(k, curr: @head, prev: @tail)
+ count = k
+ while count > 1
+ prev = curr
+ curr = curr.next
+ count -= 1
+ end
+
+ return prev if prev === curr.next
+
+ prev.next = curr.next
+ remove_each_k(k, curr: curr.next, prev: prev)
+ end
+end
+
+# @param {Integer} n
+# @param {Integer} k
+# @return {Integer}
+def find_the_winner(n, k)
+ cl = CircularList.new(n)
+ cl.remove_each_k(k).val
+end