Blog

Notes on competitive programming, machine learning, and quantitative finance by Priyanshu Debnath.

• Bin Packing — Why It's Hard, How to Approximate It, and When It Isn't Hard At All

  A full pass through bin packing — the formal problem, why the decision version is NP-complete (and why the optimization version is strongly so), every classical approximation algorithm with its proven bound, the special cases that collapse back to polynomial time, and the backtracking/bitmask-DP techniques you'd actually use to solve small instances in a contest.

• Why My PBDS ordered_multiset Solution TLE'd (and the Fenwick Fix)

  My approach to Zhily and Barknights was correct from the start, but the PBDS ordered_multiset implementation TLE'd twice. This post covers how Red-Black trees and order statistics work, and why a Fenwick tree passed instead.

• Stack, Heap, and the Registers That Finally Made Sense

  Hi, it's my first blog. I went looking for proof that the stack and heap actually exist, and found it.

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