Most programmers don’t fail because of logic—they fail because of inefficiency when constraints are tight. In competitive programming and during contests in CodeForces, LeetCode, etc., computing (a^k mod m) naively is a silent performance killer. What looks trivial quickly turns into Time Limit Exceeded when constraints scale. This is where thinking in terms of optimization—not just correctness—separates average from strong performers. Most people know this technique of Fernat's little theorem—but fail to apply it under pressure, and don't even know that it can be extended to non-primes as well. Competitive programming is less about memorising tricks and more about triggering the right pattern at the right time. Trade-off to internalize: • Naive → Simple but slow • Optimised → Slightly complex but scalable This thinking directly translates to real systems—efficient algorithms reduce latency, cost, and compute overhead at scale. Do you recognize patterns fast enough when it actually matters? Follow Vishu Kalier for more such insights. #CompetitiveProgramming #Algorithms #Coding #ProblemSolving #TimeComplexity #SystemDesign #DSA #Java #cfbr #Eternal #Codeforces #leetcode #fernattheorem
small edge case: if a%MOD= 0 then a^(MOD-1)%MOD becomes 0 and not 1. so condition gcd(a, MOD) = 1 is imp
Insightful
Insightful
Sharp take Vishu Kalier . Most people know fast exponentiation or Fermat’s Little Theorem—but freeze when it matters. Recognizing the pattern under pressure is the real skill. Optimization isn’t optional when constraints get real.
One of my favorite topics that I recommend to every beginner.
Engineering under the constraints is key 🔑
For this to work gcd must be equal to 1? And finding the tiotient function for non prime involves prime factorization which could take square root n, so use modulo exponentiation
Great one
Very insightful
This is such an insightful post—there’s a lot of depth in the ideas you’ve shared. What really stood out to me is how clearly the key learnings are articulated and connected to core fundamentals. It’s easy to come across content that sounds good on the surface, but this actually gives something meaningful to reflect on and apply. I especially appreciate how you broke down the concepts in a way that makes them actionable. It encourages readers to rethink their current approach and look at things from a more structured and intentional perspective. Posts like this don’t just inform—they genuinely influence how we think and grow. Thanks for sharing this—definitely one of those posts worth revisiting multiple times to absorb the full value.