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给定排序数组arr和整数k，不重复打印arr中所有相加和为k的不降序三元组
例如, arr = [-8, -4, -3, 0, 1, 2, 4, 5, 8, 9], k = 10，打印结果为：
-4 5 9
-3 4 9
-3 5 8
0 1 9
0 2 8
1 4 5

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

class RsData{
    public int a;
    public int b;

    public RsData(int a, int b) {
        this.a = a;
        this.b = b;
    }
}

class RsData3{
    public int a;
    public int b;
    public int c;

    public RsData3(int a, int b, int c) {
        this.a = a;
        this.b = b;
        this.c = c;
    }
}

public class Main {

    public static Scanner sc = new Scanner(System.in);

    public static List<RsData> twoAns(int[] arr, int left, int right, int k){
        List<RsData> pairList = new ArrayList<>((right - left) / 2);
        int i = left;
        int j = right;
        while(i < j){
            int a = arr[i];
            int b = arr[j];
            if(a + b == k){
                pairList.add(new RsData(a, b));
                j--;
                while (i < j && arr[j] == b){
                    j --;
                }
                i++;
                while (i < j && arr[i+1] == a){
                    i++;
                }
            }else if(a + b < k){
                i ++;
            }else {
                j --;
            }
        }
        return pairList;
    }

    public static List<RsData3> threeAns(int[] arr, int left, int right, int k){
        List<RsData3> ans = new ArrayList<>((right - left) / 3);
        int i = left;
        while (i <= right - 2){
            if(i > left && arr[i] == arr[i-1]){
                i++;
            }
            int val = arr[i];
            int twoLeft = i + 1;
            int twoRight = right;
            int twoK = k - val;
            List<RsData> twoAns = twoAns(arr, twoLeft, twoRight, twoK);
            if(twoAns != null && ! twoAns.isEmpty()) {
                for (RsData pair : twoAns) {
                    ans.add(new RsData3(val, pair.a, pair.b));
                }
            }
            i++;
        }
        return ans;
    }

    public static void dealTwo(){
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++){
            arr[i] = sc.nextInt();
        }
        List<RsData> pairList = twoAns(arr,0,n-1,k);
        for(RsData rsData: pairList){
            Integer a = rsData.a;
            Integer b = rsData.b;
            System.out.println(String.format("%d %d", a, b));
        }
    }

    /*
    10 10
    -8 -4 -3 0 1 2 4 5 8 9
    */
    public static void dealThree(){
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++){
            arr[i] = sc.nextInt();
        }
        List<RsData3>  pairList = threeAns(arr,0,n-1,k);
        for(RsData3 pair3: pairList){
            Integer a = pair3.a;
            Integer b = pair3.b;
            Integer c = pair3.c;
            // 过滤结果适应牛客网，实际应删除如下3行
            if(a.equals(b)){
                continue;
            }
            System.out.println(String.format("%d %d %d", a, b, c));
        }
    }

    public static void main(String[] args) {
        dealThree();
    }

}