Array-Left-Rotation.java

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {

        //initializing regular code...
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int d = s.nextInt();
        int[] arr = new int[n];
        for(int i = 0; i < n; i++)
            arr[i] = s.nextInt();

        //for optimal solution, if n==d or d is multiple of n then we do nothing.
        //example: move array of 5 elements, 5 place to the left. We do nothing.
        //Therefor we remove from d the multiple of n.

        //if d is not multiple of n
        if(d%n != 0) {
            if(d > n) {
                while(d>n) {
                    //here we remove n from d. (But we need to check when to stop.)
                    if(d < n)
                        break;
                    d -= n;
                }
            }
            /*
            after all the work we got d that is 100% less than n. which is good, so we don't need to do mutliple
            rotations to get to the same result.

                                           My optimal solution:

            Create new list of size n. Add all elements from arr[] to new list, starting from index d (included)
            up to index arr.length (which is n) . That way only the "rotating elements from left to right" will
            be added later, and the "not rotating elements from left to right" are added immidietly, without checking.
            */

            int[] newArr = new int[n];
            for(int i = 0; i < (n - d); i++)
                newArr[i] = arr[d+i];

            //we done adding all "non rotating elements"
            //now append all "moving elements"
            //they are in arr[] from index (include) 0 to index (include) d-1 .

            for(int i = 0; i < d; i++)
                newArr[n-d+i] = arr[i];

            //and we done!
            //print result
            for(int i = 0; i < n; i++)
                System.out.print(newArr[i] + " ");
        }
        else 
            //print result
            for(int i = 0; i < n; i++)
                System.out.print(arr[i] + " ");
    }
}