240229_TIL

백준 27433 팩토리얼

n! 재귀함수

package Baekjoon;

import java.util.Scanner;

public class B27433 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner sc = new Scanner(System.in);

		Long n = sc.nextLong();

		System.out.println(factorial(n));
	}

	public static Long factorial(Long n) {

		if (n == 0 || n == 1)
			return 1L;
		else
			return n * factorial(n - 1);
	}

}

 

백준 10870 피보나치

0과 1에 주의할 것

package Baekjoon;

import java.util.Scanner;

public class B10870 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		
		Long n = sc.nextLong();
		
		System.out.println(fibonacci(n+1));
		

	}

	public static Long fibonacci(Long n) {
		
		if(n==1) 
			return 0L;
		else if (n==2)
			return 1L;
		else {
			return fibonacci(n-2)+fibonacci(n-1);
		}
	}

}

 

백준 2447 별찍기

package Baekjoon;

import java.util.Scanner;

public class B2447 {

	static char[][] arr;

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();

		arr = new char[N][N];

		star(0, 0, N, false);

		StringBuilder sb = new StringBuilder();
		
		for (int i = 0; i < N; i++) {
			for (int j = 0; j < N; j++) {
				sb.append(arr[i][j]);
			}
			sb.append('\n');
		}
		System.out.print(sb);
	}

	static void star(int x, int y, int N, boolean blank) {

		if (blank) {// 공백
			for (int i = x; i < x + N; i++) {
				for (int j = y; j < y + N; j++) {
					arr[i][j] = ' ';
				}
			}
			return;
		}

		if (N == 1) { 
			arr[x][y] = '*';
			return;
		}

		int size = N / 3;
		int count = 0;
		for (int i = x; i < x + N; i += size) {
			for (int j = y; j < y + N; j += size) {
				count++;
				if (count == 5) { // blank 별이 4개 찍히고 1칸 공백
					star(i, j, size, true);
				} else {
					star(i, j, size, false);
				}
			}
		}
	}
}