Pow(x, n)

LeetCode 50. Fast-exponentiation `x^n` with negative-exponent handling. Classic Meta phone-screen warm-up. Requirements Implement pow(x, n) with n possibly negative. O(log |n|) via iterative or recursive squaring. Edge: n = INT_MIN (use -n carefully; cast to long or handle as a special case). Notes Interviewer may ask for both iterative and recursive versions. Common bug: integer overflow when negating INT_MIN; common follow-up: pow(x, n) mod p for modular exponentiation. Preparation Memorize iterative squaring template. Drill modular-pow variant (pow(x, n, p)) — appears as the natural follow-up.