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  1. Practice
  2. Data Structures
  3. Arrays
  4. Left Rotation
  5. Discussions

Left Rotation

  • ajaycarnet + 6 comments

    This is my C# sharp code.

            string[] s1 = Console.ReadLine().Split(' ');
        int n = int.Parse(s1[0]);
        int k = int.Parse(s1[1]);

        string[] s = Console.ReadLine().Split(' ');
        int[] array = new int[n];

        ////pre-rotation of array method:
        //-----------------------------------Right rotation
        //for (int i = 0; i < n; i++)
        //{
        //    array[(i + k) % n] = int.Parse(s[i]);
        //}

        //------------------------------------Left rotation
        for (int i = 0; i < n; i++)
        {
            array[(i + (n-k)) % n] = int.Parse(s[i]);
        }

        for (int i = 0; i < n; i++)
        {
            Console.WriteLine(array[i]+" ");
        }
    • axaysd + 0 comments

      THANK YOU SO MUCH FOR THIS SOLUTION!!!!!!!!!!!!!!!!!!!! :')

      I've been searching for both right & left shift formulae!!!

    • jdnark + 0 comments

      This code will fail the test. This is the fix:

      for (int i = 0; i < n; i++) { Console.Write(array[i]+" "); }

      Console.WriteLine();

    • ermaneesh007 + 1 comment

      Very slow. & it will not work out 1,000,000,000 records

      • aayush_break + 0 comments

        exactly...it's better to follow up with "Reversal algorithm". Follows O(n) time complexity without the usage of any temp storage. Hence saves storage and time both

    • Pree92tham + 0 comments

      Not the desired approach but it gets the job done though

      static void Main(String[] args) { string[] token=Console.ReadLine().Split(' '); int n=Convert.ToInt32(token[0]); int k=Convert.ToInt32(token[1]); string[] arr1=Console.ReadLine().Split(' '); int [] arr=Array.ConvertAll(arr1,int.Parse);

          int temp=0;
   Queue<int> l=new Queue<int>();

    for(int i=0;i<n;i++){
        l.Enqueue(arr[i]);
    }

    for(int j=0;j<k;j++){
        temp=l.Dequeue();
        l.Enqueue(temp);


    }

    foreach(int i in l){
        Console.Write("{0} ",i);
    }

}
    • nicholas_mahbou1 + 0 comments

      Great solution ajaycarnet. I compared yours with my own and yours is much faster.

          var sw = Stopwatch.StartNew();
    int[] array = new int[n];

    for(int i = 0; i < n; i++)
        array[(i + (n - d)) % n] = int.Parse(s[i]);
    sw.Stop();

    for(int i = 0; i < n; i++)
        Console.Write(array[i] + " ");

    Console.WriteLine();
    Console.WriteLine(sw.ElapsedTicks);     // 5 ticks

    sw = Stopwatch.StartNew();
    int[] a1 = Array.ConvertAll(s, Int32.Parse);
    int[] buffer = new int[d];
    Array.Copy(a1, 0, buffer, 0, d);
    Array.Copy(a1, d, a1, 0, a1.Length - d);
    Array.Copy(buffer, 0, a1, a1.Length - d, d);
    sw.Stop();

    foreach(var num in a1)
        Console.Write(num + " ");

    Console.WriteLine();
    Console.WriteLine(sw.ElapsedTicks);     // 700+ ticks
    • indyHarcourt + 0 comments

      My C# code:

      var inString = Console.ReadLine().Split(' ');
	var size = int.Parse(inString[0]);
	int d = int.Parse(inString[1]);
	var inString_temp = Console.ReadLine().Split(' ');
	List<int> seq = Array.ConvertAll(inString_temp,Int32.Parse).ToList();			

	int pointer;
	for (pointer = d; pointer < seq.Count; pointer++)
	{
		Console.Write($"{seq[pointer]} ");
	}
	for (pointer = 0; pointer < d; pointer++)
	{
		Console.Write($"{seq[pointer]} ");
	}