[Solved] Reorder array based on passed in value

a = ['A', 'B', 'C', 'D', 'C']
target="C"

a.partition { |e| e==target }.reduce(:+)
  #=> ["C", "C", "A", "B", "D"]

or

a.select { |e| e==target }.concat(a.reject { |e| e==target })
  #=> ["C", "C", "A", "B", "D"]

a is not modified.