Reorder (with.Java)

In this post, we learned how to reorder a list of integers to create a new array by changing the order of the indexes to match a rule.

We’ll do this by solving a coding test problem, reflecting on the problem we solved, and learning about other ways to solve it.

Let’s start with the problem

Problem

Given a list of integers num_list and an integer n, complete the solution function so that it returns a list that divides num_list by the elements after the nth element and the elements up to the nth element, with the elements after the nth element preceded by the elements up to the nth element.

Example input and output

My solution to the problem

import java.lang.reflect.Array;
class Solution {
    public int[] solution(int[] num_list, int n) {
        int[] answer = new int[num_list.length];
        for(int i = n; i < num_list.length; i++){
            answer[i - n] = num_list[i];
        }
        } int k = 0;
        for(int j = num_list.length - n; j < num_list.length; j++){
            answer[j] = num_list[k++];
        }
        } return answer;
    }
}

Solution

int[] answer = new int[num_list.length];: Create an array answer to store the result.

This array has the same size as num_list.

The first iteration (for(int i = n; i < num_list.length; i++) {): copies the elements from n to the end of the array into the front part of the array answer. This copies the back part of the rotated array to the front part of the answer array.

Second iteration (for(int j = num_list.length - n; j < num_list.length; j++) {): Copies the elements from the front part of the rotated array, num_list.length - n to the end, into the back part of the answer array. This copies the front part of the rotated array to the back part of the answer array.

return answer;: Returns the answer array that finally stores the rotated array.