Check if a String is Rotation of Another String?

Short answer: bool IsRotation(string s1, string s2) { if (s1.Length != s2.Length) return false; string doubled = s1 + s1; return doubled.Contains(s2); } Follow on: Explanation: If s2 is rotation of s1, it must be substring of s1+s1.

Example code

bool IsRotation(string s1, string s2) {
if (s1.Length != s2.Length) return false;
string doubled = s1 + s1;
return doubled.Contains(s2);
} Follow on: Explanation: If s2 is rotation of s1, it must be substring of s1+s1.

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.