package csdn2022.pyramid;
import java.util.Scanner;
public class Pyramid {
    public static void main(String[] args) {
    //we try printing a solid pyramid.
        Scanner sc = new Scanner(System.in);
        System.out.println("------------------------------------------");
        System.out.println("请输入你想得到的金字塔的层数：");
        int floors = sc.nextInt();
        for (int i = 1; i <= floors; ++i) {
            /*
                print " " before print "*"
                The number of " " is (floors - i),
                actually it's Total floor number minus current floor number.
                打印出每层中 * 前面的空格，实际上空格的数量 = 总的楼层数 - 当前层编号。
            */
            for (int k = 1; k <= (floors - i); ++k) {
                System.out.print(" ");
            } //第一个for打印出每层前面的空格
            for (int j = 1; j <= (2*i-1); ++j) {
                System.out.print("*");
            } //第二个for打印出每层的 * 
            System.out.println();
              //两个for完了，换行打印下一层
        }
        System.out.println("------------------------------------------");
        sc.close();
    }
}

package csdn2022.pyramid;
import java.util.Scanner;
public class HollowPyramid {
    public static void main(String[] args) {
    //requirement : 打印出空心金字塔
        int floors;
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入空心金字塔总的楼层数");
        floors = sc.nextInt();  //Enter the total number of floors
        for (int i = 1; i <= floors; ++i) {
            for1 :
            for (int t = 1; t <= (floors - i); ++t) { //the number of " " boil down to (floors - i3)
                System.out.print(" ");
            }
            /*
                上面这个for1循环是为了打印出每层前面的空格数
                而我们之前在讲金字塔的思路分析时，就已经说过每层前面的空格数是怎么来的。
             */
            for (int j = 1; j <= (2*i - 1); ++j) {  //remember here is "<="
                if (j == 1 || j == (2*i - 1) || i == floors) {      //Determine if it's the first position and the last position
                    System.out.print("*");
                } else {
                    System.out.print(" ");  //if it isn't, print the blank.
                }
            }
            System.out.println();
        }
        System.out.println("------------------------------------------");
        sc.close();
    }
}

package csdn2022.pyramid;
import java.util.Scanner;
public class HollowLozenge {
    public static void main(String[] args) {
    //requirement: print a hollow lozenge[ˈlɑːzɪndʒ] 打印一个空心菱形
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入你想获得的菱形的规模：（以半个菱形的高度为基准）");
        int floors;
        floors = sc.nextInt();
    //top half 上半部分代码原理与空心金字塔一致
        for (int i = 1; i <= floors; ++i) {
            for (int t = 1; t <= (floors - i); ++t) {
                System.out.print(" ");
            }
            for (int j = 1; j <= (2*i - 1); ++j) {  //remember here is "<="
                if (j == 1 || j == (2*i - 1)) {     //Determine if it's the first position and the last position
                    System.out.print("*");          //if it is, print the real element.
                } else {
                    System.out.print(" ");          //if it isn't, print the blank.
                }
            }
            System.out.println();
        }
//(The method of Try numbers is YYDS) 下半部分代码一时不易理解，但大家记住：试数法永远滴神
        //bottom half 下半部分
        for (int i = 1; i < floors; ++i) {//注意打印下半部分时，外层for循环这里变成 < 了，而不再是 <=
            for (int t = 1; t <= i; ++t) {
                System.out.print(" ");
            }
                /*
                    lozenge:top half and bottom half share the middle line,
                    so bottom half lacks one line.
                    in bottom half,the number of " " is just i(equals floors numerically)
                */
            for (int j = 1; j <= 2*(floors - i) - 1; ++j) {
                if (j == 1 || j == (2*(floors - i) - 1)) {
                    System.out.print("*");
                } else {
                    System.out.print(" ");  //if it isn't, print the blank.
                }
            }
            System.out.println();
            /*
            How to understand the bottom half' code？
                //（level - i） is truly likely the reverse arrangement: (下半部分像一个倒置排列的上半部分-1行)
                    like floors = 5,
                    floors - 1 = 4;
                    floors - 2 = 3;
                    floors - 3 = 2;
                    floors - 4 = 1;
                so (floors - i)= like positive-going arrangement.
                //remember it is "<=".
                //Determine if it's the first position and the last position.
            */
        }
        sc.close();
    }
}