Priority queue java

Java queue

import java.util.*;

Queue<Integer> queue = new LinkedList<Integer>();
// use non-primative types when constructing

// to add a value to the back of queue:
queue.add(7);

// to remove and return front value:
int next = queue.remove();

// to just return front value without removing:
int peek = queue.peek();

Priority queue java

import java.util.Arrays;

public class PriorityQueue {
  private int[] items = new int[5];
  private int count;

  // O(n)
  public void add(int item) {
    if (isFull())
      throw new IllegalStateException();

    var i = shiftItemsToInsert(item);
    items[i] = item;
    count++;
  }

  public boolean isFull() {
    return count == items.length;
  }

  private int shiftItemsToInsert(int item) {
    int i;
    for (i = count - 1; i >= 0; i--) {
      if (items[i] > item)
        items[i + 1] = items[i];
      else
        break;
    }
    return i + 1;
  }

  // O(1)
  public int remove() {
    if (isEmpty())
      throw new IllegalStateException();

    return items[--count];
  }

  public boolean isEmpty() {
    return count == 0;
  }

  @Override
  public String toString() {
    return Arrays.toString(items);
  }
}

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