PPractick

The problem

This is the letter version of the inverted triangle: the first row holds the first n letters of the alphabet, and every row after it drops the last letter, until only A remains. It combines the shrinking row length from Pattern 5 with the character arithmetic from Pattern 14, so it's a quick check that you can mix a shape rule with a value rule without mixing them up.

Example for n = 5:

ABCDE
ABCD
ABC
AB
A

Function signature

vector<string> reverseLetterTriangle(int n);  // row i: the first n - i + 1 letters

Test cases

Input n	Output rows	Explanation
1	"A"
3	"ABC", "AB", "A"	Each row drops its last letter
5	"ABCDE", "ABCD", "ABC", "AB", "A"

(Confirm: 1 ≤ n ≤ 26; letters without separators.)

How interviewers phrase it

• "Print a reverse letter triangle: ABCDE, ABCD, ..., A."
• Paired with Pattern 14: "Now print the letter triangle upside down."

Clarifying questions to ask

1. Uppercase? Is N at most 26?
2. Separators between letters?
3. Print or return?

Follow-ups to expect

1. "What controls the row length?"
2. "What controls the letters?"
3. "How would each row end on the same letter instead?"
4. "Complexity?"

Related questions

• Easy and Medium Easy
• Hard Easy
• Pattern 1 Easy
• Pattern 2 Easy
• Pattern 3 Easy
• Pattern 4 Easy

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