Implement 64-bit modular exponentiation safely
SalesforceSoftware Engineer · Technical Screen
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This question evaluates proficiency in modular arithmetic, safe 64‑bit integer operations, and algorithmic techniques for overflow‑resistant modular multiplication and exponentiation.
Implement a function to compute (a^b) mod m where 0 ≤ a,b < 2^61−1 and 1 ≤ m < 2^61−1 using only 64-bit operations without overflow. Provide implementations for fast modular multiplication that avoids overflow and fast modular exponentiation. Include comprehensive tests and analyze the time and space complexity.
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