Java：无法打印出这种类似金字塔的反转数字模式

Question

我需要知道如何打印出以下图案：

感谢您提供的所有帮助。我到目前为止是这样的：

for (int i = 1; i <= num; i++) 
        {
            for (int j = 1; j <= i; j++) 
            { 
                System.out.print(j+" "); 
            } 
             
            System.out.println(); 
        }
     for (int i = num-1; i >= 1; i--)
            {
                for (int j = 1; j <= i; j++)
                {
                    System.out.print(j+" ");
                }
                 
                System.out.println();
            }

它输出这个：

所以我理解了模式本身的结构，但似乎我需要以某种方式反转流程。这是我不明白的。

Answer 1

改变循环条件如下图：

public class Main {
    public static void main(String[] args) {
        int num = 5;
        for (int i = num; i >= 1; i--) {// Start with num and go downwards up to 1
            for (int j = i; j <= num; j++) {// Start with i and go upwards up to num
                System.out.print(j + " ");
            }

            System.out.println();
        }
        for (int i = 2; i <= num; i++) {// Start with 2 and go downwards up to num
            for (int j = i; j <= num; j++) {// Start with i and go downwards up to num
                System.out.print(j + " ");
            }

            System.out.println();
        }
    }
}

输出：

Answer 2

已接受的答案未输出正确的模式，所以...此代码有效。

有两个循环，每个循环逐行迭代。第一个从5到1，第二个从2到5.

在每次迭代（每一行）中，将在第一个数字旁边打印以下数字。

int num = 5;
for(int i = num ; i > 0 ; i--){
    System.out.print(i+" "); //Print the first number of the line
    for(int j = 1; j <= num-i; j++){
    //Print as extra number as line need (first line = 0 extra numbers, 
    //second line = 1 extra number...)
        System.out.print((i+j)+" ");
    }
    System.out.println();  //New line
}
for (int i = 2; i <= num; i++) { //Print second part starting by 2
    for (int j = i; j <= num; j++) { //Print extra numbers
        System.out.print(j+" ");
    }
    System.out.println(); //New line
}

并且输出符合预期：

Java：无法打印出这种类似金字塔的反转数字模式

Java: Having trouble printing out this pyramid-like reversed number pattern

java

loops

nested-loops