Long-form write-ups for the problems in this repository that are solved more than once in the source tree — brute force, memoized, tabulated, space-optimized.

Each page walks the whole progression and shows why each step is forced by the previous one's failure, with the measured verdict for every version: what times out, what overflows the stack, what actually passes. These are the problems where reading only the optimal solution teaches you the least.

Pages are grouped below by what "solved more than once" actually means for that family, because the thing that connects one approach to the next is different in each: dynamic programming (one recurrence, four implementations), graphs (genuinely different algorithms, chosen not forced), trees (recursive vs iterative vs traversal property), and data structures (Fenwick tree vs segment tree vs merge-sort counting). Sections appear as their first page lands.

Filenames stay flat — NNN-problem-slug.md — so a page's path never changes once it is linked.

One recurrence, implemented four or five ways. The page is about why each step is forced by the previous one's failure.

Java source for every solution lives under src/main/java/com/svetanis/algorithms/.