This round of Div2 is easier than average. Every problem is not so complex. Most of them are thinking or implementation problem. Not hard, just have many small logics.
E. Almost Fault-Tolerant Database
It is a problem of thinking ability. Just consider the scenario of n=2 and extend it to other situations.
D. Genius's Gambit
Just a simple construction problem. The most complex part is not how to construct it but how to implement it after I know how to construct.
C. Maximum width
Solution
Greedy. Find the $p$ with the number as large as possible and $p'$ with number as small as possible.
The $p$ match from right to left, so that can make $p_i$ largest. Similarly, $p'$ match from left to right, so that can make $p'_i$ smallest. Then the maximum width is: $\max\limits_{{1}\leq{i}<{m}}{(p_{i+1}-p'_i)}$。
Code
The sample data and I are too weak. It can pass the sample data even I forgot read the input at all.
B. Card Deck
Solution
Greedy. Pick the card with maximum value from remain deck.
Because of the coefficient in front is $n^{n-1}$! Which is a very huge number.
Code
A. Three swimmers
Solution
Take remainder for everyone. If one of remainder is 0, then need 0 second. Otherwise original time minus reminder is the time needed to wait this person.
Code
