JD并集

并集

给你两个集合，要求{A} + {B}。 注：同一个集合中不会有两个相同的元素。

我的方法（1）超出时间限制

public static void Union(int []a,int []b){
        Set<Integer>set=new HashSet<>();
        for (int i:a
             ) {
            set.add(i);
        }
        System.out.println(set.size());
        for (int i:b
                ) {
            set.add(i);
        }
        System.out.println(set.size());
        Iterator<Integer> s=set.iterator();
        List<Integer>list=new ArrayList<>();
        while(s.hasNext()){
            list.add(s.next());
        }
        Collections.sort(list);
        int i=0;
        while(i<list.size()){
            System.out.print(i);
            if (i==(list.size()-1)){

            }else{
                System.out.print(" ");
            }
        }

    }

我的方法（2）超出时间限制

 public static void Union(int []a,int []b){
      int len=a.length+b.length;
        int []c=new int [len];
        for (int i=0;i<len;i++){
            if (i<a.length){
                c[i]=a[i];
            }
            else{
                c[i]=b[i-a.length];
            }
        }

        Arrays.sort(c);
        int i=0;
        while(i<c.length){
            System.out.print(i);
            if (i==(c.length-1)){

            }else{
                System.out.print(" ");
            }
        }


    }

别人的方法 用TreeSet

public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        TreeSet<Integer> set = new TreeSet<Integer>();
        while(in.hasNext()){
            int m = in.nextInt();
            int n = in.nextInt();
            for(int i=1; i<=m+n; i++){
                set.add(in.nextInt());
            }
            Iterator<Integer> it = set.iterator();
            while(it.hasNext()){
                System.out.print(it.next());
                if(it.hasNext())
                    System.out.print(" ");
            }
        }
    }