Questions That Don't Deserve Their Own Blog — I guess it'd be good to have something like this as a place to ask random questions about problems ("I accidentally my code, wat do?") without having your blog post get downvotebombed?
(sum over edges incident on vertex 
(same as above for the right part)
are assigned to the left and right part of the graph and if they're fixed, finding the optimal 
for example for an almost complete bipartite graph Next: I was upsolving DCJ problems during the second practice round (which ended yesterday). The only non-final problem I didn't manage to solve in time was highest_mountain and only because it gives me weird RE.
I'm merging O(nodes) small convex hulls of size O(N / nodes) by sending only every K-th point in each hull, merging them in master and sending back the range that remains in the merged convex hull; then, each node sends just the smallest O(N / nodes / K) leftmost or rightmost points of this range to each other node and each node recomputes the convex hull of its own O(N / nodes) points plus all O(N / K) points it got sent.
I proved that this is correct and it passes the small subproblem (with K = 10, nodes = 10, N = 1000), while slightly incorrect implementations don't, so it really should be correct. I also verified that it passes at least one official maxtest, but gives RE later.
The cause of RE should not be too much stuff sent, since each node sends/receives only O(N / K) of data (numerically 2-3 MB, I tried "if this array is too large then return 0" checks and it changed nothing too). The memory limit shouldn't be exceeded too.
Any ideas? Btw don't forget about GCJ/DCJ last online rounds this weekend.
