알고리즘입문(Java) - HashMap,TreeSet 5. k번째 큰 수

 

(풀이)

import java.util.*;
class Main {
    public int solution(int[] arr, int n, int k){
        int answer=-1;
        TreeSet<Integer> Tset = new TreeSet<>(Collections.reverseOrder());
        for(int i=0; i<n; i++){
            for(int j=i+1; j<n; j++){
                for(int l=j+1; l<n; l++){
                    Tset.add(arr[i]+arr[j]+arr[l]);
                }
            }
        }
        int cnt=0;
        //Tset.remove(143);
        //System.out.println(Tset.size());
        //System.out.println("first : "+ Tset.first());
        //System.out.println("last : "+ Tset.last());

        for(int x : Tset){
            //System.out.println(x);
            cnt++;
            if(cnt==k) return x;
        }
        return answer;
    }

    public static void main(String[] args){
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n=kb.nextInt();
        int k=kb.nextInt();
        int[] arr=new int[n];
        for(int i=0; i<n; i++){
            arr[i]=kb.nextInt();
        }
        System.out.println(T.solution(arr, n, k));
    }
}