Calculate power of a number without built-in pow()?

Short answer: public double Power(double x, int n) { if (n == 0) return 1; double half = Power(x, n / 2); if (n % 2 == 0) return half * half; else return n > 0 ? x * half * half : (half * half) / x; } Explanation: Uses fast exponentiation (divide and conquer) to calculate x^n in O(log n).

Example code

public double Power(double x, int n) {
if (n == 0) return 1;
double half = Power(x, n / 2);
if (n % 2 == 0)
return half * half; else return n > 0 ? x * half * half : (half * half) / x;
} Explanation: Uses fast exponentiation (divide and conquer) to calculate x^n in O(log n).

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.