We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  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]} ");
	}