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.

## 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.