Increasing odd-length number rows print consecutive digits 1..i with no spaces, where row lengths grow by 2: 1, 3, 5, 7, 9.
Rule: for odd i = 1, 3, 5, … max_n
print digits 1..i (no spaces)
1
123
12345
1234567
123456789 ← max_n = 9The outer loop’s range(..., 2) is the whole trick — a clear follow-up after the jump triangle in Program 21.
Walk odd lengths with range(..., 2); on each row print j from 1 to i with end="".
| Method | Idea | Best for |
|---|---|---|
| Outer step 2 | range(..., 2); inner 1..i | Learning, interviews |
| input() max | Same loops; force odd max if needed | Interactive practice |
| Odd-only digits | Inner loop also uses step 2 | Variant practice |
for i from 1 to max_n step 2:
for j from 1 to i:
print j (same line, no spaces)
print newline| Goal | Pattern |
|---|---|
| Set max | max_n = 9 |
| Outer loop | for i in range(1, max_n + 1, 2): |
| Inner loop | for j in range(1, i + 1): |
| Print digit | print(j, end="") |
| End row | print() |
| Force odd max | if max_n % 2 == 0: max_n -= 1 |
| Odd digits only | for j in range(1, i + 1, 2): |
| API | Effect | Use for |
|---|---|---|
print(j, end="") | Stays on the same line, no space | Each digit |
print() | Ends the current line | After the inner loop |
Glue digits with end="", then break once with print(). Using end=" " adds spaces; putting print() inside the inner loop prints one digit per line.
Change the maximum odd length and the pattern updates instantly. Even values are adjusted down by 1.
max_n = 5Trace each odd value of i and the digits concatenated on that row.
i | Inner j | Printed row |
|---|---|---|
1 | 1 | 1 |
3 | 1 2 3 | 123 |
5 | 1 2 3 4 5 | 12345 |
Next odd i would be 7 — row length grows by exactly 2 each time.
Three complete programs: fixed max_n = 9, input() max, and odd-only digits. Use View Output for sample results.
max_n = 9Hard-coded maximum — outer step 2, inner concatenates 1..i.
max_n = 9
for i in range(1, max_n + 1, 2):
for j in range(1, i + 1):
print(j, end="")
print()1. Outer step. i runs 1, 3, 5, 7, 9 — those are the row lengths.
2. Inner digits. Print j from 1 to i with end="" so digits glue together.
3. End the row. print() moves to the next line after the digit string is done.
Read the maximum at runtime; if it is even, subtract 1 so the last row stays odd-length.
max_n = int(input("Enter the maximum value: "))
if max_n % 2 == 0:
max_n -= 1
for i in range(1, max_n + 1, 2):
for j in range(1, i + 1):
print(j, end="")
print()1. Read max. Convert the prompt answer with int().
2. Oddify if needed. If even, max_n -= 1 keeps an odd last length.
3. Safer input tip. Bare int(input()) raises ValueError on letters. Prefer:
raw = input("Enter the maximum value: ").strip()
try:
max_n = int(raw)
except ValueError:
print("Enter a positive whole number.")
raise SystemExit(1)
if max_n < 1:
print("Enter a positive whole number.")
raise SystemExit(1)range(..., 2)Keep max_n = 9 but print only odd digits on each row.
max_n = 9
for i in range(1, max_n + 1, 2):
for j in range(1, i + 1, 2):
print(j, end="")
print()1. Same outer loop. Row lengths are still 1, 3, 5, 7, 9.
2. Skip evens. Inner range(..., 2) prints only 1, 3, 5, … up to i.
3. Compare shapes. Rows are shorter than Example 1 because half the digits are skipped.
Check these before calling the solution done.
Using range(1, max_n + 1) prints every length 1, 2, 3, … — not only odd lengths. Keep step 2.
Use end="", not end=" ", if you want tight digit strings like 12345.
If print() is inside the inner loop, each digit lands on its own line.
With max_n = 8, the last odd i is 7 — or call max_n -= 1 first so intent is explicit.
Output is just 1 on one line.
Letters crash bare int(input()) — wrap in try/except and require max_n >= 1.
| Program | Time | Extra space |
|---|---|---|
| Examples 1–2 | O(n²) | O(1) |
| Example 3 | O(n²) | O(1) (fewer digits, same order) |
Total digits for odd lengths = 1 + 3 + 5 + … + n ≈ (n/2)² → still O(n²).
i, glue digits 1..i with end="".range(..., 2) makes lengths 1, 3, 5, 7, 9.print() advances after each row.O(n²) for maximum length n.One line: step the outer loop by 2, and glue digits 1 through i together on each row.
Each row length increases by 2 because the outer loop uses range(..., 2) (1, 3, 5, 7, 9). The inner loop prints 1..i with end="" — total prints grow as O(n²) for maximum row length n.
Continue with the next pattern in the Python number-pattern series.
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