글 읽기 - [자바] 메모리 초과가 발생하는 이유가 무엇일까요?

mommoo 3년 전 0

아래 코드에서 메모리 초과가 의심되는 부분이 있을까요??
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        int N = Integer.parseInt(reader.readLine());

        while (N-- > 0) {
            StringTokenizer tokenizer = new StringTokenizer(reader.readLine());
            int documentCount = Integer.parseInt(tokenizer.nextToken());
            int targetPosition = Integer.parseInt(tokenizer.nextToken());
            PrintQueue printQueue = PrintQueue.from(reader.readLine());

            int count = computeCountUntilFindPosition(printQueue, targetPosition);
            writer.write(String.valueOf(count));
            writer.newLine();
        }

        reader.close();
        writer.close();
    }

    private static int computeCountUntilFindPosition(PrintQueue printQueue, int position) {
        int count = 0;
        while (true) {
            count ++;
            PrintDocument document = printQueue.pop();
            if (document.isEqualsPosition(position)) {
                return count;
            }
        }
    }

    private static class PrintDocument {
        private final int position;
        private final int priority;

        public PrintDocument(int position, int priority) {
            this.position = position;
            this.priority = priority;
        }

        public boolean isEqualsPriority(int priority) {
            return this.priority == priority;
        }

        public boolean isEqualsPosition(int position) {
            return this.position == position;
        }
    }

    private static class PrintQueue {
        private final TreeMap<Integer, Integer> priorityCounter;
        private final LinkedList<PrintDocument> documents;

        private PrintQueue(LinkedList<PrintDocument> documents) {
            this.documents = documents;
            this.priorityCounter = createPriorityCounter(documents);
        }

        private static TreeMap<Integer, Integer> createPriorityCounter(List<PrintDocument> documents) {
            TreeMap<Integer, Integer> priorityCounter = new TreeMap<>();
            for (PrintDocument document : documents) {
                int priority = document.priority;
                int count = priorityCounter.getOrDefault(priority, 0);
                priorityCounter.put(priority, count + 1);
            }
            return priorityCounter;
        }

        public static PrintQueue from(String stringDocuments) {
            String[] sDocuments = stringDocuments.split(" ");
            return new PrintQueue(IntStream.range(0, sDocuments.length)
                                           .mapToObj(index -> new PrintDocument(index, Integer.parseInt(sDocuments[index])))
                                           .collect(Collectors.toCollection(LinkedList::new)));
        }

        private int popNextPriority() {
            int nextPriority = priorityCounter.lastKey();

            int nextCount = priorityCounter.get(nextPriority) - 1;
            if (nextCount == 0) {
                priorityCounter.remove(nextPriority);
            }

            return nextPriority;
        }

        public PrintDocument pop() {
            int nextPriority = popNextPriority();

            while (true) {
                PrintDocument document = documents.removeFirst();
                if (document.isEqualsPriority(nextPriority)) {
                    return document;
                }
                documents.addLast(document);
            }
        }
    }
}
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[자바] 메모리 초과가 발생하는 이유가 무엇일까요?

mommoo 3년 전 0

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