DSA interview question

Understanding Recursion: Print a Message N Times

Easy · Algorithms · Topics: recursion, basics

The problem

Before recursion shows up in trees, backtracking and dynamic programming, you need a rock-solid picture of what actually happens when a function calls itself. The simplest possible example is printing a message N times without a loop. A function prints the message once and then asks a smaller copy of itself to print it N − 1 more times. The exercise is less about the output and more about being able to explain the three parts every recursive function needs: a base case, a recursive case, and progress toward the base case. It's also a chance to see the call stack, and what happens when the base case is missing.

Example: printMessage(3, "Hi") prints Hi three times.

Function signature

void printMessage(int n, const string& msg);  // prints msg n times, one per line

Test cases

Input `(n, msg)`	Output	Explanation
(3, "Hi")	`Hi` / `Hi` / `Hi`	Three calls print; the fourth hits the base case
(1, "Go")	`Go`	One print, then the base case
(0, "Hi")	(nothing)	Base case immediately
(5, "Practice")	`Practice` five times	Maximum recursion depth is 6 calls

(Confirm: n ≥ 0; each message is printed on its own line; no loops allowed.)

How interviewers phrase it

"Print your name N times without using a loop."
Theory questions: "What is recursion? What's a base case? What happens if you forget it? What is the call stack?"
Often asked to freshers as a lead-in to "Print 1 to N" and "Print N to 1" using recursion.

Clarifying questions to ask

Can N be 0 or negative?
How large can N be? (Very deep recursion can overflow the stack.)
Is printing directly fine, or should the output be collected?

Follow-ups to expect

"What happens without a base case?"
"What's on the call stack?"
"What's the time and space complexity?"
"Is recursion slower than a loop?"
"What's tail recursion?"

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