java 中同时包含数字和字母的三角形

Question

I want to write a Java program that prints a special triangle

Answer 1

Printing a triangle like that usually involves a loop with an index counter.

If we write down the counter value, and the ASCII code / Unicode code point for the characters, we can see a pattern we can use.

       1         0: 49
      AAA        1:    65
     33333       2: 51
    CCCCCCC      3:    67
   555555555     4: 53
  EEEEEEEEEEE    5:    69
 7777777777777   6: 55
GGGGGGGGGGGGGGG  7:    71

For even values of the index, we can print character with ASCII code i + 49 , and for odd values we print i + 64 .

In Java 11+, it can be done as follows. I'll leave it as an exercise for people to fix themselves if they need a solution for versions of Java before 11.

static void printTriangle(int size) {
    for (int i = 0; i < size; i++) {
        System.out.println(" ".repeat(size - i - 1) +
                           Character.toString(i + (i & 1) * 15 + 49).repeat((i << 1) + 1));
    }
}

Output when calling printTriangle(8)

       1
      AAA
     33333
    CCCCCCC
   555555555
  EEEEEEEEEEE
 7777777777777
GGGGGGGGGGGGGGG

Output when calling printTriangle(10)

         1
        AAA
       33333
      CCCCCCC
     555555555
    EEEEEEEEEEE
   7777777777777
  GGGGGGGGGGGGGGG
 99999999999999999
IIIIIIIIIIIIIIIIIII

Answer 2

Here is the correct code:

    Scanner sc = new Scanner(System.in);
    char lastChar = sc.next().charAt(0);   

    int totalLines = lastChar - 'A' + 1;

    for (int i=0; i<totalLines; i++)
    {
        for(int j=1; j<totalLines-i; j++)
            System.out.print(" ");
        
        for (int k=1; k<=2*i+1; k++)
        {
            if (i%2 == 0)
                System.out.print(i+1);
            else
                System.out.print((char)('A'+i-1));
        }
        
        System.out.println();
    }