C++ Reverse Alphabet Pyramid Pattern (Slice from E)
Beginner
7 min read
Updated: Sep 2026
3 programs
Live preview
Definition
What Is This Pattern?
A right-aligned reverse alphabet pyramid prints a growing reverse slice each row — from a single top letter down to a full E D C B A base — with padding so the block stays right-aligned.
Remember
Rule: for i from top down to 'A',
print pads for A..(i-1), then letters top..i (width 2)
E
E D
E D C
E D C B
E D C B A ← top = 'E' (monospace)
Companion to Program 22: same fixed-width grid (two spaces for pads + setw(2) for letters), but each row prints a reverse slice top..i instead of a running sequential counter.
Approach
How to Solve It
Two ways to emit the same shape — start with char loops, then optionally rewrite with int row indexes.
Method
Idea
Best for
Char loops
Outer i; pad A..(i-1); letters top..i
Learning, interviews, exams
Int row index
Pad n - row; print row letters from top down
When you think in row numbers
Pseudocode
Pseudocode
for i from top down to 'A':
for j from 'A' to (i - 1):
print " "
for j from top down to i:
print j in width-2 field
print newline
Print cells without a newline, then end the row once. Include <iomanip> for setw.
Try it
Live Preview
Change the top letter and the right-aligned reverse pyramid updates instantly.
One letter from A to F. Tap a chip or type a letter — the preview redraws as you go.
Live resultTop E · 5 rows · 15 letters
E
E D
E D C
E D C B
E D C B A
Trace
Worked Walkthrough — Top = E
Trace each row’s pads, reverse slice, and printed line (each cell is width 2).
i
Pad cells
Letters
Printed row
E
4
E
E
D
3
E D
E D
C
2
E D C
E D C
B
1
E D C B
E D C B
A
0
E D C B A
E D C B A
Row count = top - 'A' + 1 (5 for E). Letter total: 1 + 2 + 3 + 4 + 5 = 15 = 5×6/2.
Code
C++ Programs
Three complete programs: fixed top letter, cin input, and an int-index rewrite. Use View Output to reveal sample results.
Example 1 — Fixed A–E
Hard-coded top E — pad first, then print letters from E down to the current row letter.
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char i, j;
for (i = 'E'; i >= 'A'; i--) {
for (j = 'A'; j < i; j++)
cout << " ";
for (j = 'E'; j >= i; j--)
cout << setw(2) << j;
cout << "\n";
}
return 0;
}
Output
E
E D
E D C
E D C B
E D C B A
How It Works
1. Outer loop descends.i runs from 'E' down to 'A' — one row per letter.
2. Pad first. Print " " for each j from 'A' to i - 1 so the letters stay right-aligned.
3. Reverse slice. Print j from 'E' down to i with setw(2) (width-2 cells).
4. Break the line.cout << "\n" after both inner loops starts the next row.
When i = 'C', pads run for A and B, then letters print E D C.
Example 2 — Top Letter Input
Read the top letter at runtime. Prefer validating a single A–Z character in real apps.
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char top, i, j;
cout << "Enter the top letter (like E): ";
cin >> top;
for (i = top; i >= 'A'; i--) {
for (j = 'A'; j < i; j++)
cout << " ";
for (j = top; j >= i; j--)
cout << setw(2) << j;
cout << "\n";
}
return 0;
}
Output (when user enters C)
Enter the top letter (like E): C
C
C B
C B A
How It Works
1. Prompt and read. Ask for a top letter with cin >> top.
2. Same pad/letter core. Both the outer start and the letter-loop start use top.
3. Safer input tip. Check the stream and require A–Z:
Safer input
if (!(cin >> top) || top < 'A' || top > 'Z') {
cout << "Enter one letter from A to Z.\n";
return 1;
}
Example 3 — Int Row Index
Same shape with integer indexes: pad n - row cells, then print row letters from the top down.
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char top = 'E';
int n = top - 'A' + 1;
int row, s, k;
for (row = 1; row <= n; row++) {
for (s = 0; s < n - row; s++)
cout << " ";
for (k = 0; k < row; k++)
cout << setw(2) << (char)(top - k);
cout << "\n";
}
return 0;
}
Output
E
E D
E D C
E D C B
E D C B A
How It Works
1. Derive height.n = top - 'A' + 1 is 5 when top is 'E'.
2. Pad by row number. Row 1 pads n - 1 cells; the last row pads 0.
3. Letters from the top. Letter k is (char)(top - k) — row 1 prints E; row 5 prints E..A.
Edge Cases & Pitfalls
Check these before calling the solution done.
Single space
Broken alignment
Pads must be " " (two spaces) to match setw(2). One space skews the pyramid in monospace output.
\n inside
Broken outline
If cout << "\n" sits inside either inner loop, each cell lands on its own line. Print pads and letters without a newline; end the row only after both loops.
j <= i
Extra pad cell
The pad loop must stop at j < i, not j <= i, or you insert one too many empty cells.
top = A
Single letter
Output is just a width-2 A cell. Pad loop never runs. A good sanity check.
top < A
Empty output
Outer loop never runs if top < 'A'. Validate A–Z before looping.
cin fail
Check the stream
If cin fails, top may be unset — always test if (!(cin >> top)) and require A–Z.
Analysis
Time and Space Complexity
Program
Time
Extra space
Char loops (Examples 1–2)
O(n²)
O(1)
Int row index (Example 3)
O(n²)
O(1)
For n = top - 'A' + 1 rows, each row does up to O(n) pad + letter writes. Letter total = 1 + 2 + … + n = n(n + 1)/2.
Remember
Key Takeaways
Rule: for i from top down to 'A', pad A..(i-1), then print top..i.
Fixed width: use " " pads and setw(2) so every cell is two columns.
Break the row:cout << "\n" only after both inner loops.
Complexity:O(n²) time; O(1) extra space.
One line: for each row letter i from top down to A, print pads for A..(i-1), then letters top..i with width 2, then a newline.
Frequently Asked Questions
The first prints padding so the visible letters are right-aligned. The second prints letters from E (or your top letter) down to the current row letter i.
Each letter is printed in a width-2 field, so two spaces keep empty cells the same width and the pyramid aligned in monospace output.
Program 22 uses one running counter k++ across all rows (A..O). Program 23 prints a reverse slice each row using the loop variable j (E..i).
cout stays on the same line for pads and letters. cout << "\n" ends the row after both inner loops finish.
Yes. Change the second loop to always begin from your chosen top letter and decrement to the row letter — Example 2 does this with user input.
O(n²) for n rows because each row does O(n) work across the padding + letter loops.
Use cin >> top, require A–Z (or a–z then toupper), and reject failed input. Cap at Z if you only want alphabetic ranges.
For top = E, when i is E you print 4 pad cells (A..D); when i is A you print 0. Pads = (i − A).
🤔
Did you know?
Outer i runs from E down to A. The first inner loop prints one " " per j with A <= j < i (so the block shifts left each row). The second loop prints letters from E down to i using setw(2) so each cell is 2 columns wide.
