A right-aligned alphabet pyramid prints growing prefixes of the alphabet (A, A B, A B C, …) pushed right with leading spaces so every row shares the same right edge.
Remember
Rule: for row letter i from 'A' to top,
print (top - i) spaces, then A..i (width 2)
A
A B
A B C
A B C D
A B C D E ← top = 'E'
Unlike Program 22, letters restart from A on every row. Unlike Program 16, this only right-aligns — it does not fully center the pyramid.
Approach
How to Solve It
Two ways to emit the same shape — char loops with pads, then optionally rewrite with int row indexes.
Method
Idea
Best for
Char loops
Pad top..i+1; print A..i with setw(2)
Learning, interviews, exams
Int row index
Pad n - row; print row letters from A
When you think in row numbers
Pseudocode
Pseudocode
for i from 'A' to top:
for j from top down to (i + 1):
print " "
for k from 'A' to i:
print k in width-2 field
print newline
Cheat sheet
Goal
Pattern
Walk each row
for (char i = 'A'; i <= top; i++)
Leading spaces
for (char j = top; j > i; j--) cout << ' ';
Prefix letters
for (char k = 'A'; k <= i; k++) cout << setw(2) << k;
Print pads and letters without a newline, then end the row once. Include <iomanip> for setw.
Try it
Live Preview
Change the top letter and the right-aligned pyramid updates instantly — including the letter total.
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
A
A B
A B C
A B C D
A B C D E
Trace
Worked Walkthrough — Top = E
Trace each row’s pad count, letter prefix, and printed line (letters use width-2 cells).
i
Pad spaces
Letters
Printed row
A
4
A
A
B
3
A B
A B
C
2
A B C
A B C
D
1
A B C D
A B C D
E
0
A B C D E
A B C D E
Pad count = top - i. Letters always restart at A. Total letters: 1 + 2 + 3 + 4 + 5 = 15 = 5×6/2.
Code
C++ Programs
Three complete programs: fixed A–E, top-letter input with cin, and an int-index rewrite. Use View Output to reveal sample results.
Example 1 — Fixed A–E
First print leading spaces, then print letters A..i using setw(2).
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char i, j, k;
for (i = 'A'; i <= 'E'; i++) {
for (j = 'E'; j > i; j--)
cout << ' ';
for (k = 'A'; k <= i; k++)
cout << setw(2) << k;
cout << "\n";
}
return 0;
}
Output
A
A B
A B C
A B C D
A B C D E
How It Works
1. Outer loop picks the row end.i runs from 'A' to 'E' — one growing prefix per row.
2. Pad first. Print one space for each j from 'E' down while j > i.
3. Restart letters. Print k from 'A' through i with setw(2).
4. Break the line.cout << "\n" after both inner loops starts the next row.
When i = 'C', two leading spaces print, then letters A B C.
Example 2 — Top Letter Input
The pattern prints up to that row. Prefer validating a single A–Z character in real apps.
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char top, i, j, k;
cout << "Enter top letter (like E): ";
cin >> top;
for (i = 'A'; i <= top; i++) {
for (j = top; j > i; j--)
cout << ' ';
for (k = 'A'; k <= i; k++)
cout << setw(2) << k;
cout << "\n";
}
return 0;
}
Output (when user enters C)
Enter top letter (like E): C
A
A B
A B C
How It Works
1. Prompt and read.cin >> top stores one character as the shared upper bound.
2. Same pad + prefix core. Pad count is always top - i; only the shared top letter changes.
3. Safer input tip. Prefer:
Safer input
char top;
if (!(cin >> top) || top < 'A' || top > 'Z') {
cout << "Enter one letter from A to Z.\n";
return 1;
}
Example 3 — Int Row Index
Often clearer if you think in row numbers: pad n - row spaces, then print row letters from A.
C++
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
char top = 'E';
int n = top - 'A' + 1;
int row, s, L;
for (row = 1; row <= n; row++) {
for (s = 0; s < n - row; s++)
cout << ' ';
for (L = 0; L < row; L++)
cout << setw(2) << (char)('A' + L);
cout << "\n";
}
return 0;
}
Output
A
A B
A B C
A B C D
A B C D E
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 spaces; the last row pads 0.
3. Letters from A. Letter L is (char)('A' + L) — row 1 prints A; row 5 prints A..E.
Edge Cases & Pitfalls
Check these before calling the solution done.
k++
Continuous stream by mistake
If you keep a running k++ across rows, you get Program 22-style output. Restart the letter loop at 'A' each row.
No pads
Left-aligned instead
Skipping the space loop prints a left-aligned triangle. Keep j from top down while j > i.
cout "\n" inside
Broken outline
If cout << "\n" is 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.
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 read
cin >> top can fail or leave a lowercase letter. Prefer 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 prints up to O(n) spaces plus O(n) letters. Letter total = 1 + 2 + … + n = n(n + 1)/2.
Remember
Key Takeaways
Rule: for row i, print top - i spaces, then letters A..i.
Restart A: every row begins the letter loop at 'A' — not a running k++.
Break the row: call cout << "\n" only after both inner loops.
Complexity:O(n²) time; O(1) extra space.
One line: for each row letter i from A to top, print top - i spaces, then A..i with width 2, then cout << "\n".
Frequently Asked Questions
The first inner loop prints (E - i) leading spaces, fewer on each lower row, so the letter block ends at the same right edge.
Width-2 formatting prints each letter in an even column so the output matches the spaced layout (best viewed in a monospace font).
Program 22 uses a continuous k++ stream across all rows. Program 27 restarts letters from A on every row and uses leading spaces to push rows to the right.
Remove the leading-space loop and print letters directly from A to the row letter.
cout << ch stays on the same line for each pad or letter. cout << "\n" ends the row after both inner loops.
O(n²) for n rows because each row prints O(n) spaces plus O(n) letters.
Use cin >> top, require A–Z (or a–z), and reject failed input. Cap at Z if you only want alphabetic ranges.
Yes. Pad n − row spaces, then print row letters as char('A' + L). Example 3 on this page shows that style.
🤔
Did you know?
Leading padding: for each row letter i, the loop prints E - i spaces. Then the letter loop prints A through i using setw(2) so columns look even in monospace output. The last row has no padding; all rows share the same right edge.
