3rd Dan Ashen Sorting, brute force, modular arithmetic, and first DP steps 0/15 to pass · 20 problems
5th Dan Torrent Graph traversal, DSU, binary search on the answer, and combinatorics 0/15 to pass · 20 problems
6th Dan Azure Shortest paths, subsequence DP, number theory, and clever counting 0/15 to pass · 20 problems
7th Dan Solar Binary lifting, bitmask DP, segment-tree thinking, and exchange arguments 0/15 to pass · 20 problems
9th Dan Crimson Game theory, rerooting tree DP, and inventive constructions 0/15 to pass · 20 problems