YoungForest's blog

Returning to algorithm competition for interest, four problems restore the joy of reasoning through symmetry, geometry, terrain and graph structure.

An after-contest record finds the second-largest digit, manages expiring tokens and greedily extends consecutive values; problem four remains unfinished.

How a local route setting fixed an Ubuntu VPN connection that reached private research resources but blocked the public internet.

Four solutions test one swap, find a star centre, greedily improve pass ratios, and expand from a fixed index for the best subarray score.

Four solutions find an aligned point, test distinct powers of three, sum substring frequency gaps, and count degree pairs with repeated-edge correction.

Three contest solutions handle one bit segment, a target-sum gap and restricted paths; post-contest grouped DP makes window XOR zero.

Three contest solutions filter items, search dessert costs and balance array sums; a post-contest monotonic stack computes car collisions.

After a macOS update stopped qBittorrent from opening, I kept the security checks and documented an afternoon of building Qt, Boost, and libtorrent.

A historical note on adding an ad script to Hexo NexT, verifying the site and configuring ads.txt through two integration paths.

Four solutions complete the latest valid time, minimize character changes, rank prefix-XOR coordinates, and binary-search the smallest box footprint.