[백준] 2742번 : 기찍 N - Java

https://www.acmicpc.net/problem/2742

2742번: 기찍 N

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참고 문제

https://unknownomad.tistory.com/97

[백준] 2741번 : N 찍기

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구현 방법

1. 입력

• Scanner
• BufferedReader

 

2. 출력

• System.out.println()
• BufferedWriter
• StringBuilder

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풀이

1. Scanner + System.out.println()

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int N = in.nextInt();
        in.close();
        
        while(N > 0) {
            System.out.println(N);
            N--;
        }
    }
}

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2. BufferedReader +  System.out.println()

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
 
public class Main {
    public static void main(String[] args) throws IOException {
    
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        br.close();
        
        while(N > 0) {
            System.out.println(N);
            N--;
        }
    }
}

 

3. BufferedReader + BufferedWriter

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
 
public class Main {
    public static void main(String[] args) throws IOException {
    
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        
        int N = Integer.parseInt(br.readLine());
        br.close();
        
        while(N > 0) {
            bw.write(N + "\n");
            N--;
        }
        bw.flush();
        bw.close();
    }
}

 

4. BufferedReader + StringBuilder

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
 
public class Main {
    public static void main(String[] args) throws IOException {
    
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        
        int N = Integer.parseInt(br.readLine());
        br.close();
        
        while(N > 0) {
            sb.append(N + "\n");
            N--;
        }
        System.out.println(sb);
    }
}

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성능

• BufferedReader > Scanner
• BufferedWriter / StringBuilder > System.out.println()

 

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출처 : https://st-lab.tistory.com/32