Solve the "Find the Celebrity" problem?

Short answer: public int FindCelebrity(int n, Func<int, int, bool> knows) { int candidate = 0; for (int i = 1; i < n; i++) { if (knows(candidate, i)) candidate = i; } for (int i = 0; i < n; i++) { if (i != candidate && (knows(candidate, i) || !knows(i, candidate))) return -1; } return candidate; } Explanation: First find candidate by elimination, then verify candidate. Follow on:

Example code

public int FindCelebrity(int n, Func<int, int, bool> knows) {
int candidate = 0;
for (int i = 1; i < n; i++) {
if (knows(candidate, i)) candidate = i;
}
for (int i = 0; i < n; i++) {
if (i != candidate && (knows(candidate, i) || !knows(i, candidate))) return -1;
}
return candidate;
} Explanation: First find candidate by elimination, then verify candidate. Follow on:

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.