CalcTopTen.java

package datastructure.priorityqueue;

import org.junit.Test;

import java.util.PriorityQueue;
import java.util.Queue;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

public class CalcTopTen {

    /*
        TASK
        많은 수 중 top 10을 구한다.
     */

    @Test
    public void test() {
        TopTen t = new TopTen();
        t.put(1);
        t.put(2);
        t.put(3);
        t.put(4);
        t.put(5);
        t.put(6);
        t.put(7);
        t.put(8);
        t.put(9);
        t.put(10);
        t.put(11);
        t.put(12);
        t.put(19);
        t.put(21);
        t.put(13);
        int[] arr = new int[10];
        int j = 0;
        for (int i = arr.length; i > 0; i--) {
            arr[j] = i;
            j++;
        }
        assertThat(t.getTop10(), is(arr));
    }

    public class TopTen {
        private Queue<Integer> queue = new PriorityQueue<>();

        private void put(int data) {
            queue.add(data);
        }

        private int[] getTop10() {
            int[] arr = new int[10];
            for (int i = arr.length - 1; i >= 0; i--) {
                arr[i] = queue.poll();
            }
            return arr;
        }

        private void read(int n) {
            if (queue.size() < 10) {
                queue.offer(n);
            } else {
                int tenth = queue.peek();
                if (n > tenth) {
                    queue.poll();
                    queue.offer(n);
                }
            }
        }
    }
}