java로 여러가지 모양의 별 찍어보기

오른 직각 삼각형

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int n = Integer.parseInt(br.readLine());

    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < n; i++) {
      sb.append(" ".repeat(n - i - 1));
      for (int j = 0; j < i + 1; j++) {
        sb.append("*");
      }
      sb.append("\n");
    }
    System.out.println(sb);

왼쪽 직각 삼각형

    StringBuilder sb1 = new StringBuilder();
    for (int i = n; i > 0; i--) {
      for (int j = 0; j < i; j++) {
        sb1.append("*");
      }
      sb1.append("\n");
    }
    System.out.println(sb1);

    System.out.println("____________________");

 

마름모꼴

import java.io.*;

public class Main {
  public static void main(String[] args) throws IOException {
    StringBuilder sb2 = new StringBuilder();
    for (int i = 0; i < n; i++) { // 0 >> 3
      sb2.append(" ".repeat(n - i - 1));
      for (int j = 0; j < i + 1; j++) {
        sb2.append("*");
      }
      sb2.append("\n");
    }
    for (int j = n - 1; j > 0; j--) { // 3 >> 0
      sb2.append(" ".repeat(n - j));
      for (int z = 0; z < j; z++) {
        sb2.append("*");
      }
      sb2.append("\n");
    }
    System.out.print(sb2);
  }
}

 

예쁜 마름모

StringBuilder sb3 = new StringBuilder();
    for (int i = 0; i < n; i++) { // 0 >> 3
      sb3.append(" ".repeat(n - i - 1));
      for (int j = 0; j < i * 2 + 1; j++) {
        sb3.append("*");
      }
      sb3.append("\n");
    }

    for (int j = n - 1; j > 0; j--) { // 3 >> 0
      sb3.append(" ".repeat(n - j));
      for (int z = 0; z < j * 2 - 1; z++) {
        sb3.append("*");
      }
      sb3.append("\n");
    }
    System.out.print(sb3);

    System.out.println("____________________");

0: o
1: oo
2: ooo
3: oooo
4: ooo 4 >3 1
5: oo 5 >2 3
6: o 6 >1 5
7:         7

---

   o  1 > 3 n-1
  oo  2 > 2 n-2
 ooo  3 > 1 n-3
oooo 4 > 0
 ooo 3 > 1
  oo
   o


    o
   oo
  ooo
 oooo
ooooo
 oooo
  ooo
   oo
    o