377B:Preparing for the Contest

bsearch on days, and then use a pq on feasible students, but by cost. The key insight is that we can reuse the pq on the next sgement, because the previous capabily ones are still solid!!!

501D:Misha and Permutations Summation

Uses factorial number systems

652D:Nested Segments

A common pattern of solving 2-d problem with the help of a 1-d D.S. Uses fenwick tree!!!

301B: Yaroslav and Time

binary search answer + Bellman-Ford