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  1. import java.util.*;
  2.  
  3. class MergeArray{
  4. 	int[] A;
  5. 	private int[] tmp;
  6. 	private int k;
  7. 	private int cnt;
  8. 	public void merge_sort(int p, int r) {		//배열 A를 클래스 멤버 변수로
  9. 		int q;
  10. 	    if (p < r) {
  11. 	        q = (p + r) / 2;
  12. 	        merge_sort(p, q);
  13. 	        merge_sort(q + 1, r);
  14. 	        merge(p, q, r);
  15. 	    }
  16. 	}
  17.  
  18. 	private void merge(int p, int q, int r) {
  19. 		int i = p;
  20. 		int j = q + 1;
  21. 		int t = 0;			//배열은 0부터 시작하기에 0으로 초기화
  22. 	    while (i <= q && j <= r) {
  23. 	        if (A[i] <= A[j])
  24. 	        	tmp[t++] = A[i++];
  25. 	        else  
  26. 	        	tmp[t++] = A[j++];
  27. 	    }
  28. 	    while (i <= q)
  29. 	        tmp[t++] = A[i++];
  30. 	    while (j <= r)
  31. 	        tmp[t++] = A[j++];
  32. 	    i = p; t = 0;		//바로 위 주석과 같은 이유
  33. 	    while (i <= r) {
  34. 	    	A[i++] = tmp[t++];
  35. 	    	cnt++;
  36. 	    	if(cnt == k) {
  37. 	    		System.out.println(A[i - 1]);
  38. 	    		System.exit(0);
  39. 	    	}
  40. 	    }
  41. 	}
  42.  
  43. 	MergeArray(int n, int k){
  44. 		A = new int[n];
  45. 		tmp = new int[n];
  46. 		this.k = k;
  47. 		cnt = 0;
  48. 	}
  49. }
  50.  
  51. class Ideone{
  52.     public static void main(String[] args){
  53.     	Scanner sc = new Scanner(System.in);
  54.     	int n = sc.nextInt();
  55.     	int k = sc.nextInt();
  56.  
  57.     	MergeArray m = new MergeArray(n, k);
  58.     	for(int i = 0; i < n; i++)
  59.     		m.A[i] = sc.nextInt();
  60.     	m.merge_sort(0, n - 1);		//배열은 0부터 n-1까지이기 때문에
  61.     	System.out.println(-1);
  62.     	sc.close();
  63.     }
  64. }
Success #stdin #stdout 0.13s 52820KB
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-1
https://ideone.com/OYw7Ix
language:
Java (HotSpot 12)
created:
2 years ago
visibility:
secret

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