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Write a program to print the following pattern:
A
A B
A B C
A B C D
A B C D E

Java Code Example — Pattern Programs

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Write a program to print the following pattern:
A
A B
A B C
A B C D
A B C D E

Objective

Write a Java program to print a right-angled triangle using alphabet characters.

Algorithm / Approach

  1. Use an outer loop with a char variable (i) running from 'A' to 'E'.
  2. Inside, use an inner loop with a char variable (j) running from 'A' to i.
  3. Print the character j followed by a space.
  4. Print a newline at the end of the outer loop.
Test.java 
class Test {
 public static void main(String[] a)
 {
  for(char i = 'A'; i<='E'; i++) {
   for(char j = 'A'; j<=i; j++) {
    System.out.print(j+" ");
   }
   System.out.println();
  }
 }
}

Explanation of the Program

  • Java allows the use of char data types directly in loop counters.
  • Characters in Java are stored as ASCII (or Unicode) integer values behind the scenes. 'A' is 65, 'B' is 66, and so on.
  • By iterating j from 'A' up to the current row letter i, the program prints an increasing sequence of letters on each row.

Complexity

Time Complexity O(n2)
Space Complexity O(1)

Common Mistakes

  • Trying to print an integer and cast it to char, which is valid but makes the code much harder to read than just using char variables in the loop header.
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