我如何制作一棵行数为1、3、5、3、7、5、7、9、7和9的圣诞树

Question

如何制作一个行数为1、3、5、3、7、5、7、9、7…的圣诞树。。。？

圣诞树应该是这样的：

               x
              xxx
             xxxxx
              xxx
             xxxxx
            xxxxxxx
             xxxxx
            xxxxxxx
           xxxxxxxxx
            xxxxxxx
           xxxxxxxxx
          xxxxxxxxxxx

它要求用户输入行数。到目前为止我已经知道了。更早制造了一个pyrmamid*

import java.util.Scanner;
public class Pyramide {
    public static void main(String[] args) {
        // les inn antall rader
        System.out.println("Hvor mange rader skal pyramiden ha?");
        int antallRader;
        Scanner tastatur = new Scanner(System.in);
        antallRader = tastatur.nextInt();
        // skrive ut en kolonne som har saa mange rader som det ble angitt
        // for hver verdi som rad kan faa naar rad starter paa 1, er mindre
        // eller lik antallRader, og oekes hver gang med 1)
        // for hver verdi mellom startverdien og sluttverdien med avstand 1
        // gjenta
        for (int rad = 1; rad <= antallRader; rad++) {
            for (int antallTomt = 1; antallTomt <= antallRader - rad; antallTomt++) {
                System.out.print(" ");
            }
            for (int antallX = 1; antallX <= 2 * rad - 1; antallX++) {
                System.out.print("x");
            }
            for (int antallX = 1; antallX <= 2 * rad - 1; antallX++) {
                System.out.print("x");
            }
            System.out.println();
        }
    }
}

我想这是一个循环，不知怎么地，会变成+2，+2，-2。但是我不知道如何编程。

Answer 1

你们非常接近。请考虑：

int linjer = 0;
int radDenneGang = 1;
while (linjer < antallRader) {
    int antallRaderDenneGang;
    if (antallRader - linjer >= 3)
        antallRaderDenneGang = radDenneGang + 2;
    else
        antallRaderDenneGang = radDenneGang + antallRader - linjer - 1;
    for (int rad = radDenneGang; rad <= antallRaderDenneGang; rad++) {
        for (int antallTomt = 1; antallTomt <= antallRader - rad; antallTomt++) {
            System.out.print(" ");
        }
        for (int antallX = 1; antallX <= 2 * rad - 1; antallX++) {
            System.out.print("x");
        }
        // for (int antallX = 1; antallX <= 2 * rad - 1; antallX++) {
        // System.out.print("x");
        // }
        System.out.println();
    }
    linjer += antallRaderDenneGang - radDenneGang + 1;
    radDenneGang++;
}

使用antallRader=15，它可以生产出以下美丽的圣诞树：

          x
         xxx
        xxxxx
         xxx
        xxxxx
       xxxxxxx
        xxxxx
       xxxxxxx
      xxxxxxxxx
       xxxxxxx
      xxxxxxxxx
     xxxxxxxxxxx
      xxxxxxxxx
     xxxxxxxxxxx
    xxxxxxxxxxxxx

Answer 2

第一步可能是抽象东西。我的意思是，制作一种只打印这棵树的一行的方法：

private static void branch(int width,int centerPoint) {
    for (int i = 0; i < centerPoint - width / 2; i++) {
        System.out.print(' ');
    }
    for (int i = 0; i < width; i++) {
        System.out.print('x');
    }
}

然后你可以制作一棵你喜欢的任何形状的树：

public static void main(String... args) {
    System.out.println("Hvor mange rader skal pyramiden ha?");
    Scanner scanner = new Scanner(System.in);
    int numRows = scanner.nextInt();
    int width = 1;
    for (int i = 0;i < numRows;i++) {
        branch(width,numRows / 3 + 2);
        if (width % 3 == 2)
            width -= 2; //Reduces the width by 2 if it's line 2, 5, 8, etc.
        else
            width += 2; //Other lines, increases the width by 2.
    }
}

Answer 3

开始吧！

String x = "                xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
int ix = x.indexOf('x');
for (int i = 0; i < 12; i++) {
    int j = i/3 + i%3;
    System.out.println(x.substring(j, ix + 2*j + 1));
}

输出

            x
           xxx
          xxxxx
           xxx
          xxxxx
         xxxxxxx
          xxxxx
         xxxxxxx
        xxxxxxxxx
         xxxxxxx
        xxxxxxxxx
       xxxxxxxxxxx