[백준 1181 / 자바(JAVA)] - 단어 정렬

     

문제의 Key

 

1. TreeSet O(log n)
- null 입력은 가능하지만 한 번만 저장 가능하고 중복X
- 오름차순으로 데이터를 정렬합니다.
- 내부적으로 TreeMap을 사용
        

성능 차이 비교

: HashSet > LinkedHashSet > TreeSet

  ★ Hashset은 stream.sort을 지양하자.
- Stream sorted() returns a stream consisting of the elements of this stream, sorted according to natural order. For ordered streams, the sort method is stable but for unordered streams, no stability is guaranteed.
- The Streams API can convert an ordered stream, which may represent an ordered data source such as a list or a sorted set, into an unordered stream.
-  We can also convert an unordered stream into an ordered stream by applying an sorting intermediate operation.

   

 

 

 

package 백준.정렬;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.TreeSet;
import java.util.stream.Stream;

/*
* 메모리 :26028 KB
* 시간 : 860ms
* */
public class 단어정렬_1181 {
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int num = Integer.parseInt(br.readLine());

        String[] arr = new String[num];

        TreeSet<String> treeSet = new TreeSet<>();

        for (int i = 0; i < num; i++) {
            treeSet.add(br.readLine());
        }

        Object[] arr2 = treeSet.stream().sorted(Comparator.comparingInt(String::length)).toArray();
//                .forEach(System.out::println)
        for(Object arrrr : arr2){
            System.out.println(arrrr);
        }

/*

        TreeSet O(log n)
        - null 입력은 가능하지만 한 번만 저장 가능하고 중복될 수 없습니다.
        - 객체(데이터)를 중복 저장할 수 없지만 오름차순으로 데이터를 정렬합니다.
        - 내부적으로 TreeMap을 사용합니다.
        HashSet > LinkedHashSet > TreeSet 순서로 성능의 차이

        Hashset은 stream.sort을 지양하자.

        Stream sorted() returns a stream consisting of the elements of this stream, sorted according to natural order. For ordered streams, the sort method is stable but for unordered streams, no stability is guaranteed.

        The Streams API can convert an ordered stream, which may represent an ordered data source such as a list or a sorted set, into an unordered stream.

        We can also convert an unordered stream into an ordered stream by applying an sorting intermediate operation.

        */
    }
}

https://www.acmicpc.net/problem/1181

1181번: 단어 정렬