PPractick

The problem

This pattern combines the shrinking shape of Pattern 5 with the counting rows of Pattern 3: the first row prints 1 2 ... n, and each following row stops one number earlier, until the last row prints just 1. It checks whether you can combine two ideas you've already used: the row length comes from the row number (n − i + 1), while the printed value comes from the column (j).

Example for n = 4:

1 2 3 4
1 2 3
1 2
1

Function signature

vector<string> invertedNumberTriangle(int n);  // row i: "1 2 ... (n - i + 1)"

Test cases

Input n	Output rows	Explanation
1	"1"	One row
3	"1 2 3", "1 2", "1"	Each row counts up from 1 and ends one earlier
5	"1 2 3 4 5", "1 2 3 4", "1 2 3", "1 2", "1"

(Confirm: numbers are space-separated with no trailing space; some judges print them without spaces.)

How interviewers phrase it

• "Print this inverted number triangle for N."
• Often asked straight after Pattern 3: "Now print the same thing upside down."

Clarifying questions to ask

1. Space-separated numbers or not?
2. Trailing spaces allowed?
3. Print or return?

Follow-ups to expect

1. "Which loop controls the length and which controls the value?"
2. "How would you print n n−1 ... 1 in each row instead?"
3. "What's the 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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