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Task/Quickselect-algorithm/Ruby/quickselect-algorithm.rb

@@ -0,0 +1,18 @@
+def quickselect(a, k)
+  arr = a.dup # we will be modifying it
+  loop do
+    pivot = arr.delete_at(rand(arr.length))
+    left, right = arr.partition { |x| x < pivot }
+    if k == left.length
+      return pivot
+    elsif k < left.length
+      arr = left
+    else
+      k = k - left.length - 1
+      arr = right
+    end
+  end
+end
+
+v = [9, 8, 7, 6, 5, 0, 1, 2, 3, 4]
+p v.each_index.map { |i| quickselect(v, i) }