Fixed. Thank you!

The SIT & JUB STAR Contest is not rated.

UPD: Got it after 10 minutes

It is the same as all Codeforces rounds. Please, read https://codeforces.me/blog/entry/8790

For every pair of rows $$$(i, j)$$$ compute the number of rows $$$k$$$ such that $$$a[i][k] = a[j][k] = ch$$$ separately for every letter $$$ch$$$. Then the answer is the sum $$$\binom{cnt}{2}$$$.

Here with a bit of twist. We can store the array for each alphabet

How to solve H ?

For J, define $$$len[u]$$$ is the longest step we can take from $$$u$$$ to leaf node by moving down (that is $$$len[leaf] = 1$$$ and $$$len[nonLeaf] = max(len[v_1], len[v_2], ..., len[v_k]) + 1$$$ for $$$v_i$$$ are children of $$$u$$$

Observe that to pick a node we choose to teleport, we can pick any unmarked node $$$u$$$ with maximum $$$len[u]$$$ and move all the way down to its child to the leaf (obviously we need to move to a child with the largest $$$len$$$). And after taking down, simply mark all of its path to the leaf. Do this for each teleportation

Starting from the leaf with the deepest depth, mark all nodes as visited as you go up, until you reach another visited node, then store the number of nodes as a path. Do it from deepest to shallowest.

For each vertex calculate longest path from it to some leaf and to which vertex you should go to achieve this. Now let's have a heap, initially with only vertex 1, where vertex at the top has longest path. On each step we take vertex from the heap, go through the path and add all adjacent vertices to the vertices on the path that are not themselves on the path. When heap is empty we pad answer with ns

For L I tried mobius transform to count each subset scares how many bandits. Looks correct, but failed at test 14. Not sure why.

For L fix the hero you're going to use then iterate over multiples of $$$t_i$$$ for that hero, for each bandit in that hero's way get a mask of other heroes such that those heroes' $$$t_j$$$ don't divide this bandit's position all submasks of this mask can't be considered so to check if a mask can be considered you just need to use SOS DP.

For M binary search the answer and solve it in a backwards manner starting from any index this way you need to check that you will arrive at index $$$i$$$ in $$$answer - t_i$$$.

You can use $$$DP[L][R][Side]$$$ where $$$DP[L][R][Left] = min(DP[L+1][R][Left] + cost(L,L+1), DP[L+1][R][right] + cost(L,R))$$$ and same for right.

This way

For M have a dynamic programming with state "what smallest time I can finish task i and still need to finish all tasks from i (not including) to j (including)." You start with dp[0, n — 1] = max(t[0], abs(x[0])) and dp[n — 1, 0] = max(t[n — 1], abs(x[n — 1])) and from dp[i, j] you can go to either dp[i +- 1, j] or dp[j, i +- 1] (where + or — before one depends on direction from i to j). Answer then min dp[i, i] for all i.

For L I enumerate a hero i to deliver the treasure and enumerate all possibilities of the heroes who scare bandits in $$$O(2^{m-1})$$$.Now we need to count how many bandits on the i-th hero's path will be scared away in this state.We can use the principle of inclusion and exclusion to calculate.So the final time complexity is $$$O(m^2\times2^{m-1})$$$.

I use segment tree. We know that if we have solved $$$x$$$ number of problems, it means we can pick any unsolved problem with the least amount of time from $$$[1, 2x+1]$$$

After we pick the optimal problem, we can update the segment tree point (e.g. the problem time) to infinity (so we make sure to not pick it again since it's been solved)

I think heap is possible as well to solve this

keep a priority queue. Each round, push in next two problems, and pop one with min time. Count the sum until reach tot time. That makes it always satisfy the request.

Priority queue is also fine. Here is my implementation.

Basically every time you solve a problem, you can add two more to the PQ (until you've added everything). If you can't solve any problems, you have to exit. If you can, it's obviously advantageous to solve the shortest allowed problem (hence the PQ).

Just maintain a priority queue of eligible subjects(it basically represents the exams that you haven't taken till now but you can take them at any time). let's say we have taken count exams till now then we can add the ith exam to the above priority queue only if(i-(count+1)<=count+1). If we can't add the curr subject to the queue, then we have to pick a minimum duration subject exam from the queue. Do this till you have some remaining time.

Well, it is knapsack, you just need a neat trick to do "add a instances of delta" in O(n) (where n is knapsack size)

If you have a lot of equal objects in the knapsack, you can replace them with log new objects using powers of two and a remainder. For example 20 objects of weight $$$X$$$ can be replaced with objects $$$X,2X,4X,8X,5X$$$

This was an excellent contest — very enjoyable problems. Thanks.