Back to Top 5 (with.Java)

This is a post about the “Back to 5th” problem.

We’re going to go through a coding test problem, reflect on the problem we solved, and learn about other ways to solve it.

Let’s start with the problem.

Problem

You are given a list num_list of integers.

Complete the solution function so that it returns a list containing the five smallest numbers in num_list in ascending order.

Example input and output

My solution to the problem

import java.util.*;
class Solution {
    public int[] solution(int[] num_list) {
        int[] answer = new int[num_list.length - 5];
        Arrays.sort(num_list);
        int idx = 0;
        for(int i = 5; i < num_list.length; i++){
            answer[idx++] = num_list[i];
        }
    } return answer;
}

Solution

int[] answer = new int[num_list.length - 5];: Create a new array answer in the existing array num_list to store the remaining elements minus the first five elements. The length of this array is set to num_list.length - 5.

Arrays.sort(num_list);: Sorts the input array num_list in ascending order. The sorted array is sorted from smallest to largest value.

int idx = 0;: Initialize the index variable idx for assigning values to the array answer.

for(int i = 5; i < num_list.length; i++) : Iterate over the input array num_list, starting at index 5 and repeating to the end. This ignores the first 5 elements and selects the element after the 5th.

answer[idx++] = num_list[i];: store the value at the current index i in a new array answer, incrementing the index idx to prepare it for storage at the next location.

return answer;: finally returns a new array answer with the selected elements.

This code sorts the input array, selects the remaining elements except for the first five, and returns them in a new array. The returned array stores the elements after the 6th in the sorted array.