Why Doesn\'t PriorityQueue.toString() Return Elements in Sorted Order?

Understanding the Sorting Issue in PriorityQueue.toString

PriorityQueue, a data structure based on a binary heap, maintains elements in a partially sorted order. While it ensures that the element at the root represents the one with the highest priority, the remaining elements within the heap may not be fully sorted.

In this specific case, the PriorityQueue is used to store a list of nodes, each representing a character and its frequency. The HuffmanComparator is responsible for determining the priority of each node based on its frequency, with lower frequency nodes having higher priority.

Analyzing the Output

When calling PriorityQueue.toString, it simply converts the internal heap structure into a string representation. This does not involve sorting or any further ordering of elements. As a result, the output may not reflect the desired sorted order.

Solution: Iteratively Polling Elements

To obtain a sorted list of elements from the PriorityQueue, it is necessary to iteratively poll each element. Polling involves removing the highest priority element from the heap and rearranging the remaining elements to maintain the heap property. By repeatedly polling elements, the order of the displayed elements will gradually become sorted.

Example Code

Here is a modified version of the code that iteratively polls elements and prints them in sorted order:

<code class="java">while (!queue.isEmpty()) {
    System.out.println(queue.poll());
}</code>

This method ensures that the output elements are sorted based on the priority determined by the HuffmanComparator.

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