题解 | 小红的整数配对

import java.util.Scanner;
import java.util.Arrays;
import java.util.Scanner;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
             Scanner in = new Scanner(System.in);

        int n = in.nextInt();
        int m = in.nextInt();

        long count=0;
        int[] arr=new int[n];
        for (int i = 0; i < n; i++) {
            arr[i]=in.nextInt();
        }

        Arrays.sort(arr);

        for (int i = arr.length-1; i >0 ; i--) {
            if (arr[i]-arr[i-1]<=m){
                count=count+(long)arr[i]*arr[i-1];
                i--;
            }
        }

        System.out.println(count);
    }
}