[백준 문제] java - 15552, 2741, 2742, 11021, 11022, 2438, 2439, 10871, 10952, 10951

15552번 빠른 A+B

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

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));
			StringTokenizer st;
			int T = Integer.parseInt(br.readLine());
			for(int i = 0; i<T; i++) {
				st = new StringTokenizer(br.readLine());
				bw.write((Integer.parseInt(st.nextToken()) + Integer.parseInt(st.nextToken()) + "\n"));
			
		}
			bw.flush();
			bw.close(); 
	}
}

2741번 N 찍기

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

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());
		
		for(int i = 1; i<=N; i++) {
			System.out.println(i);
		}
		
		br.close();
	}
}

 

 

2742번 기찍 N

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

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());
		
		for(int i = N; i>=1; i--) {
			System.out.println(i);
		}
		
		br.close();
	}
}

11021번 A+B - 7

방법1 - StringTokenizer에 문자열 담기

import java.util.Scanner;
import java.util.StringTokenizer;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int T = Integer.parseInt(sc.nextLine());
		String [] arr = new String [T];
		
		for(int i = 0; i < T; i++) {
			arr[i] = sc.nextLine();	
		}
		
		for(int i = 0; i<arr.length; i++) {
			StringTokenizer st = new StringTokenizer(arr[i]);
			System.out.println( "Case #" + (i+1) + ": " + (Integer.parseInt(st.nextToken()) + Integer.parseInt(st.nextToken())) );
		}
		
		sc.close();
	}
}

방법2  - String []에 담기

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		StringBuffer sb = new StringBuffer();
		
		int T = Integer.parseInt(sc.nextLine());
		String [] arr = new String [T];
		
		for(int i = 0; i < T; i++) {
			arr[i] = sc.nextLine();
		}
		for(int i = 0; i<arr.length; i++) {
			String [] arr2 = arr[i].split(" ");
			System.out.println( "Case #" + (i+1) + ": " + (Integer.parseInt(arr2[0])+Integer.parseInt(arr2[1])) );
		}
        sc.close();
    }
  }

아래가 StringTokenizer에 넣어서 출력한거고, 위에가 String 배열에 넣어서 출력한것

메모리랑, 코드 길이가 String 배열이 더 짧고, 처리 시간은 StringTokenizer가 더 짧다.

처리가 많은 코드가 아니여서 비슷비슷 한듯

11022번 A+B - 8

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		StringBuffer sb = new StringBuffer();
		
		int T = Integer.parseInt(sc.nextLine());
		String [] arr = new String [T];
		
		for(int i = 0; i < T; i++) {
			arr[i] = sc.nextLine();
		}
		for(int i = 0; i<arr.length; i++) {
			String [] arr2 = arr[i].split(" ");
			System.out.println( "Case #" + (i+1) + ": " + arr2[0] + " + " + arr2[1] + " = " +
			(Integer.parseInt(arr2[0])+Integer.parseInt(arr2[1])) );
		}
		
		sc.close();
	}
}

2438번 별 찍기 - 1

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

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());
		
		for(int i = 0; i<N; i++) {
			for(int j = 0; j<=i; j++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}
}

2439번 별 찍기 - 2

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

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());
		
		for(int i = 0; i<N; i++) {
			for(int j = N-1; j>i; j--) {
				System.out.print(" ");
			}
			for(int k = 0; k<=i; k++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}
}

 

10871번 X보다 작은 수

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String [] arr = br.readLine().split(" ");
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		for(int i = 0; i < Integer.parseInt(arr[0]) ; i++) {
			int num = Integer.parseInt(st.nextToken());
			if(num < Integer.parseInt(arr[1])) {
				System.out.print(num + " ");
			}
		}

	}
}

10952번 A+B - 5

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true) {
			String [] arr = br.readLine().split(" ");
			if(arr[0].equals("0") && arr[1].equals("0")) {
				break;
			}
			System.out.println(Integer.parseInt(arr[0])+Integer.parseInt(arr[1]));
		}
	}
}

10951번 A+B - 4

이클립스에서는 에러가 나는데 백준에서는 정답이레요

import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true) {
			String str = br.readLine();
			if(str == null) {
				break;
			}else {
				StringTokenizer st = new StringTokenizer(str);
				System.out.println(Integer.parseInt(st.nextToken()) + Integer.parseInt(st.nextToken()));
			}
		}
	}
}