Programa Java para imprimir el patrón de triángulo de estrella inferior espejo

En este artículo, vamos a aprender cómo imprimir patrones de triángulos de estrellas inferiores en espejo en Java. 

Ilustración:

Input: number = 7
Output:
* * * * * * * 
 * * * * * * 
  * * * * * 
   * * * * 
    * * * 
     * * 
      * 
      * 
     * * 
    * * * 
   * * * * 
  * * * * * 
 * * * * * * 
* * * * * * * 

Métodos: podemos imprimir un patrón de triángulo de estrella inferior en espejo usando bucles, por lo que 

1. Uso del bucle for
2. Usando el ciclo while
3. Usando el bucle do-while

Método 1: Usar for Loop

Ejemplo

// Java program to print Mirror Lower Star Triangle Pattern
// Using For loop
import java.io.*;
 
// Main class
class GFG {
 
    // Method
    // Main driver method
    public static void main(String[] args)
    {
        // Declare and initialize variable to
        // Size of the triangle
        int number = 7;
 
        // Declaring two variables for rows and columns
        int m, n;
 
        // Outer loop 1
        // Prints the first half triangle
        for (m = 1; m <= number; m++) {
 
            // Inner loop 1
            for (n = 1; n < m; n++) {
                // Print whitespace
                System.out.print(" ");
            }
 
            // Inner loop 2
            for (n = m; n <= number; n++) {
                // Print star
                System.out.print("*"
                                 + " ");
            }
 
            // Ending line after each row
            System.out.println();
        }
 
        // Outer loop 2
        // prints the second half triangle
        for (m = number - 1; m >= 0; m--) {
 
            // Inner loop 1
            for (n = 0; n < m; n++) {
                // Print whitespace
                System.out.print(" ");
            }
 
            // Inner loop 2
            for (n = m; n <= number - 1; n++) {
                // Print star
                System.out.print("*"
                                 + " ");
            }
 
            // Ending line after each row
            System.out.println();
        }
    }
}

* * * * * * * 
 * * * * * * 
  * * * * * 
   * * * * 
    * * * 
     * * 
      * 
      * 
     * * 
    * * * 
   * * * * 
  * * * * * 
 * * * * * * 
* * * * * * * 

Método 2: usar el bucle while

Ejemplo

// Java program to Print Mirror Lower Star Triangle Pattern
// using While loop
import java.io.*;
 
// Main Class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Declare and initialize variable to
        // Size of the triangle
        int number = 7;
 
        int m = number;
        int n;
 
        // Outer loop 1
        // prints the first half triangle
 
        // Till condition holds true
        while (m > 0) {
            n = 0;
 
            // Inner loop 1
            // prints space until n++ < number - m is false
            while (n++ < number - m) {
                // print whitespace
                System.out.print(" ");
            }
 
            n = 0;
 
            // Inner loop 2
            // Prints star until n++ < (m * 2) - 1 is false
            while (n++ < (m * 2) - 1) {
                // Print star
                System.out.print("*");
            }
 
            // Ending line after each row
            System.out.println();
 
            // Decrementing by one
            m--;
        }
 
        m = 1;
 
        // Outer loop 2
        // prints the second half triangle
        while (m <= number) {
            n = 0;
 
            // Inner loop 1
            // prints space until n++ < number - m is false
            while (n++ < number - m) {
                // Print whitespace
                System.out.print(" ");
            }
 
            n = 0;
 
            // Inner loop 2
            // Prints star until n++ < (m * 2) - 1 is false
            while (n++ < (m * 2) - 1) {
                // print star
                System.out.print("*");
            }
 
            // Ending line after each row
            System.out.println();
 
            m++;
        }
    }
}

*************
 ***********
  *********
   *******
    *****
     ***
      *
      *
     ***
    *****
   *******
  *********
 ***********
*************

Producción:

Método 3: Usando do-while Loop

Implementación:

Ejemplo

// Java program to print Mirror Lower Star Triangle Pattern
// using Do-while loop
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Declare variable with the
        // Size of the triangle
        int number = 7;
 
        int m = number;
        int n;
 
        // Outer loop 1
        // prints the first half triangle
        do {
            n = 0;
 
            // Inner loop 1
            // prints space until n++ < number - m is false
            do {
                // Print whitespaces
                System.out.print(" ");
 
            } while (n++ < number - m);
 
            n = 0;
 
            // Inner loop 2
            // prints star until n++ < m * 2 - 2 is false
            do {
                // Print star
                System.out.print("*");
            }
 
            while (n++ < m * 2 - 2);
 
            System.out.println("");
 
        }
 
        // Condition check for do-while
        while (--m > 0);
 
        m = 1;
 
        // Outer loop 2
        // prints the second half triangle
        do {
            n = 0;
 
            // Inner loop 1
            // prints space until n++ < (number - m) is
            // false
            do {
                // Print whitespace
                System.out.print(" ");
 
            } while (n++ < (number - m));
 
            n = 0;
 
            // Inner loop 2
            // prints star until n++ < (m * 2) - 2 is false
            do {
                // Print star
                System.out.print("*");
            }
 
            while (n++ < (m * 2) - 2);
 
            System.out.println("");
 
        }
 
        // Condition check for do-while
        while (++m <= number);
    }
}

 *************
  ***********
   *********
    *******
     *****
      ***
       *
       *
      ***
     *****
    *******
   *********
  ***********
 *************

Complejidad del tiempo : O(N ² ) donde N es el tamaño de entrada del triángulo
Espacio auxiliar: O(n)