Sort int[] array

I’m a bit confused on how to sort this array using the following conditions:

int[] array = { 3, 15, 7, 11, 6, 4, 1, 8, 10, 13 };

The conditions are as follows:

• The largest integer is first
• The second-largest integer is last
• The third-largest integer should be second
• The pattern continues, leaving the smallest number in the middle.

For example, if the starting array is {1, 2, 3, 4, 5, 6, 7}, then the sorted array should be {7, 5, 3, 1, 2, 4, 6}.

Any help with this? I’m new to sorting algorithms, so I’m still trying to figure out the logic I should walk myself through to do something like this. Thanks in advance!

Answer

Maybe this solution copy the array too many times, but it works.

package at.ylz.playground;

import java.util.Arrays;
import java.util.Collections;

public class Main {
    public static void main(String[] args) {
//      int[] array = {3, 15, 7, 11, 6, 4, 1, 8, 10, 13};
        int[] array = {1, 2, 3, 4, 5, 6, 7};
        var sortedArray = Arrays.stream(array).boxed().sorted(Collections.reverseOrder()).mapToInt(value -> value).toArray();
        int n = array.length;
        int[] res = new int[n];
        int left = 0, right = n-1;
        while (left <= right) {
            res[left] = sortedArray[left*2];
            if(left*2+1<n)
                res[right] = sortedArray[left*2+1];
            left++;
            right--;
        }
        for (int i : res) System.out.println(i);
    }

}