An inverted repeating alphabet triangle prints a wide first row of one letter, then shrinks by one repeated letter on each new line while letters count down.
Remember
Rule: for letter i from top down to 'A',
print i exactly (i - 'A' + 1) times
EEEEE
DDDD
CCC
BB
A ← 5 rows (top = 'E')
It is the flip of Program 10: same countdown letters, but widths shrink 5, 4, 3, …, 1 instead of growing. Print the outer letter inside the inner loop so each row stays uniform.
Approach
How to Solve It
Two ways to emit the same shape — start with nested ord/chr loops, then optionally shorten with string multiplication.
Method
Idea
Best for
Nested loops
Outer = letter; inner = width; print outer letter
Learning, interviews, exams
ch * repeat
Build a whole repeated-letter row in one call
Shorter demos once loops click
Pseudocode
Pseudocode
for i from top down to 'A':
for j from 'A' to i:
print i (no newline)
print newline
Print letters without a newline, then end the row once.
Try it
Live Preview
Change the height and the inverted triangle updates instantly — including the letter total.
Whole numbers from 1 to 26 (A–Z). Tap a chip or type a value — the preview redraws as you go.
Live result5 rows · 15 letters
EEEEE
DDDD
CCC
BB
A
Trace
Worked Walkthrough — 'E' down to 'A'
Trace each outer-loop value of i and count how many times the inner loop runs.
i
Inner j range
Printed row
Repeats
'E'
'A'..'E'
EEEEE
5
'D'
'A'..'D'
DDDD
4
'C'
'A'..'C'
CCC
3
'B'
'A'..'B'
BB
2
'A'
'A'..'A'
A
1
Total letter prints: 5 + 4 + 3 + 2 + 1 = 15 = 5×6/2. That triangular sum is why time is O(n²).
Code
Python Programs
Three complete programs: fixed letters, input(), and a ch * repeat shortcut. Use View Output to reveal sample results.
Example 1 — Fixed 'E' down to 'A'
Hard-coded range — outer letter counts down; inner loop shrinks and prints that letter.
Python
top = ord('E')
for i in range(top, ord('A') - 1, -1):
for j in range(ord('A'), i + 1):
print(chr(i), end="")
print()
Output
EEEEE
DDDD
CCC
BB
A
How It Works
1. Outer loop picks the letter.i runs from ord('E') down to ord('A').
2. Inner loop sets the width.j runs from ord('A') to i — five times for E, four for D, and so on.
3. Print the outer letter.print(chr(i), end="") keeps the whole row the same character.
4. Break the line. Bare print() after the inner loop starts the next row.
Example 2 — User Input Version
Compute top = ord('A') + rows - 1, then shrink with repeat = code - ord('A') + 1. Prefer try/except ValueError in real apps.
Python
raw = input("Enter the number of rows: ").strip()
try:
rows = int(raw)
except ValueError:
print("Please enter a whole number of rows >= 1.")
else:
if rows < 1:
print("Please enter a whole number of rows >= 1.")
else:
if rows > 26:
rows = 26
top = ord('A') + rows - 1
a = ord('A')
for code in range(top, a - 1, -1):
ch = chr(code)
repeat = code - a + 1
for k in range(repeat):
print(ch, end="")
print()
Output (when user enters 4)
Enter the number of rows: 4
DDDD
CCC
BB
A
How It Works
1. Prompt and parse. Ask for a row count, then convert with int(...) inside try/except ValueError.
2. Compute the top letter. For rows = 4, top is ord('D') — first row is DDDD.
3. Same shrink core.repeat = code - ord('A') + 1 gives widths 4, 3, 2, 1 as code counts down.
4. Clamp for A–Z. Cap at 26 so codes stay in the alphabet for demos.
Example 3 — ch * repeat
Build each repeated-letter row in one call — same shape, no explicit character loop.
Python
rows = 5
top = ord('A') + rows - 1
a = ord('A')
for code in range(top, a - 1, -1):
repeat = code - a + 1
print(chr(code) * repeat)
Output
EEEEE
DDDD
CCC
BB
A
How It Works
1. Same countdown. Still walk code from top down to ord('A').
2. Build the row.chr(code) * repeat creates a string of length repeat filled with that letter.
3. Learn loops first. Use Examples 1–2 when you need to show nested bounds; treat this as a polish shortcut afterward.
Edge Cases & Pitfalls
Check these before calling the solution done.
print(j)
Stepping letters on a row
If you print chr(j) instead of chr(i), you get ABCDE on the first row. Print the outer letter to keep each row uniform.
step +1
Growing triangle by mistake
Counting letters upward with growing widths reprints Program 10’s shape family. Keep range(..., -1) from the top letter down to 'A'.
print early
Column of letters
If bare print() (or default print(chr(i))) is inside the inner loop, each letter lands on its own line. Use end="" for letters; call print() only after the inner loop.
rows > 26
Past Z
ord('A') + rows - 1 leaves A–Z when rows > 26. Clamp or reject in interactive programs.
rows = 1
Single A
Output is just A — top and tip coincide. A good sanity check.
Bad input
Catch ValueError
Bare int(input()) raises on letters — wrap in try/except ValueError and require 1–26.
Analysis
Time and Space Complexity
Program
Time
Extra space
Nested loops (Examples 1–2)
O(rows²)
O(1)
ch * repeat (Example 3)
O(rows²)
O(rows) per temporary row string
Total letters = n + (n - 1) + … + 1 = n(n + 1)/2 — still quadratic in n. Same totals as Program 10; only the print order of widths differs.
Remember
Key Takeaways
Rule: countdown letter i; print i exactly i - 'A' + 1 times.
Flip of Program 10: same letters — widths shrink instead of grow.
Break the row: call bare print() only after the inner loop.
Complexity:O(n²) time from the triangular letter count; O(1) extra space for nested loops.
One line: for i from the top letter down to 'A', print i for every j from 'A' to i, then print().
Frequently Asked Questions
Program 10 prints widths 1..5 (E, DD, CCC, ...). Program 11 prints widths 5..1 (EEEEE, DDDD, ...). Both use repeating letters per row and letters counting down.
When i is E, the inner loop runs from A through E (5 times) and prints E each time. Next i becomes D, the inner loop runs 4 times (A..D) and prints D.
The inner loop only controls how many times to print. Printing the outer letter keeps the entire row the same letter; printing the inner counter would step letters across the row.
Because the inner loop stops at j <= i (range to i + 1). Smaller i means fewer iterations, so fewer characters are printed.
print(ch, end="") stays on the same line. print() ends the current line. Letters use end=""; the row break uses print() after the inner loop.
O(n²) where n is the number of rows. Total printed characters equal n+(n-1)+…+1 = n(n+1)/2.
Yes. print(ch * repeat) prints a full repeated-letter row in one call. Nested loops are better for learning; ch * repeat is a handy shortcut later.
Use a try/except ValueError around int(input()), or check raw.isdigit() before converting, then clamp rows between 1 and 26 so bad input does not walk past Z.
🤔
Did you know?
This is the inverted twin of Program 10: letters still step E→A, but widths shrink 5, 4, 3, …, 1 instead of growing. Print the outer loop letter inside the inner loop so each row stays uniform.
