Arrays of Int arrays. Storing duplicates in order only

Question

I need to store an array of Int array for ordered duplicates (which are in a Array).

Example:

• Given array:
  mainArray = [7, 7, 3, 2, 2, 2, 1,

Answer 1

You can use the forEach and keep the value of the last element to keep adding to your array while it's not different like in this way:

let mainArray = [7, 7, 3, 2, 2, 2, 1, 7, 5, 5]

func filterTo2DArray(list: [Int] ) -> [[Int]] {

   var resultList = [[Int]]()

   list.forEach { x -> () in
      if let lastValue = resultList.last?.last where lastValue == x {
          resultList[resultList.count - 1].append(x)
      }
      else{
         resultList.append([x])
      }
   }
   return resultList
}


let t = filterTo2DArray(mainArray) //[[7, 7], [3], [2, 2, 2], [1], [7], [5, 5]]

I hope this help you.