algo. kth largest element in an array

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[] q = new int[n];
        
        for (int i = 0; i < n; i++) {
            q[i] = sc.nextInt();
        }
        
        System.out.print(find_min_k(q, 0, n - 1, k));
    }
    
    public static int find_min_k(int[] q, int l, int r, int k) {
        if (l == r) {
            return q[l];
        }
        
        int x = q[l + r >> 1];
        int i = l - 1, j = r + 1;
        
        while (i < j) {
            do i++; while (q[i] < x);
            do j--; while (q[j] > x);
            if (i < j) {
                int t = q[i];
                q[i] = q[j];
                q[j] = t;
            }
        }
        
        int rank = j - l + 1;
        if (k <= rank) return find_min_k(q, l, j, k);
        else return find_min_k(q, j + 1, r, k - rank);
    }
}