I’ve noticed that graph problems tend to feel different from most others. The difficulty rarely comes from the algorithm itself—BFS, DFS, or Dijkstra are usually already known—but from how the problem is modeled. Small changes in how nodes or edges are defined can completely change the solution. Sometimes a problem looks complex until you draw the graph, and sometimes it looks simple until you realize the graph isn’t what you first imagined. That’s probably what makes graph problems interesting to me: progress usually comes from understanding the structure, not from trying more transitions.

After getting used to thinking in terms of structure and relationships in graphs, I started appreciating data structures that feel similarly elegant. Fenwick Tree is one of those—it’s surprisingly simple on the surface, yet powerful enough to solve problems that would otherwise require much heavier machinery. The idea that you can maintain prefix information using just a few bit operations feels unintuitive at first, but once it clicks, it’s hard not to admire how clean the structure is. Like graphs, the interesting part isn’t the code itself, but how the problem reshapes once the structure fits.