Fastest algorithm for circle shift N sized array for M position

Question

What is the fastest algorithm for circle shifting array for M positions?
For example, [3 4 5 2 3 1 4] shift M = 2 positions should be [1 4 3 4 5 2 3

Answer 1

Swift 4 version for shifting array left.

func rotLeft(a: [Int], d: Int) -> [Int] {

   var result = a
   func reverse(start: Int, end: Int) {
      var start = start
      var end = end
      while start < end {
         result.swapAt(start, end)
         start += 1
         end -= 1
      }
   }

   let lenght = a.count
   reverse(start: 0, end: lenght - 1)
   reverse(start: lenght - d, end: lenght - 1)
   reverse(start: 0, end: lenght - d - 1)
   return result
}

For example, if input array is a = [1, 2, 3, 4, 5], and left shift offset is d = 4, then result will be [5, 1, 2, 3, 4]