YoungForest's blog

Post-contest notes on invalid transactions, smallest-character frequency, zero-sum list removal and multiple fixed-capacity stacks.

Three solutions use a minimum spanning tree, a coding-versus-eating boundary, and odd-even divisor analysis to classify street numbers.

Biweekly notes on a one-row keyboard, hierarchical paths, minimum-cost stick merging and village water distribution during camp.

Weekly notes on character counts, tree-level sums, multi-source distance search and greatest suffixes after a relaxed break.

Weekly notes on date arithmetic, bounded dice sums, repeated runs and range majorities, plus a lesson about forcing segment trees.

A top-100 contest review covering zigzag arrays, a tree-colouring game, change-only snapshots and greedy chunked palindromes.

Weekly notes on a three-term recurrence, a board path with a special final cell, bordered squares and memoised stone-game DP.

Kick Start notes on leaving an overcomplicated segment-tree path for a direct parity rule and the longest valid interval.

Biweekly notes on largest unique values, Armstrong numbers, minimum spanning trees and topological ordering, finished with time to spare.

Three post-contest solutions move from brute force to structured algorithms through grid skipping, matrix intervals and compressed state.