알고리즘 - 백준, 2522 별 찍기 - 12

import java.io.*;
import java.util.*;

public class Main{
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        
        int value = Integer.parseInt(br.readLine());
        int length = value*2 -1;
        
        
        for(int i=1; i<= length; i++){
            if(i<=value){
                for(int j=1; j<=value-i; j++){
                    sb.append(" ");
                }
                for(int k=1; k <= i; k++){
                    sb.append("*");
                }
            }
           if(i> value){
              for(int j=1; j<=(i-value); j++){
                      sb.append(" ");
              }
                  for(int k=1; k<=(2*value- i); k++){
                      sb.append("*");
              }
           }
            sb.append("\n");
        }
        String result = sb.toString();
        System.out.print(result);
        
    }   
}