Find the nth Fibonacci Number?

Short answer: int Fibonacci(int n) { if (n <= 1) return n; int a = 0, b = 1; for (int i = 2; i <= n; i++) { int temp = a + b; a = b; b = temp; } return b; } Explanation: Iterative DP approach; each Fibonacci number is sum of two previous. Follow on:

Example code

int Fibonacci(int n)
{
if (n <= 1) return n;
int a = 0, b = 1;
for (int i = 2; i <= n; i++)
{
int temp = a + b;
a = b;
b = temp;
}
return b;
} Explanation: Iterative DP approach; each Fibonacci number is sum of two previous. 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.