D.Armchairs(EducationalCodeforcesRound109(RatedforDiv.2)题解)xiaodangao
题目链接[D.Armchairs](http//codeforces.com/contest/1525/problem/D)
M.StoneGames（ICPC2020昆明题解）xiaodangao
题目链接[M.StoneGames](https//ac.nowcoder.com/acm/contest/12548/M)
D.CutandStick(CodeforcesRound#716(Div.2)题解)xiaodangao
题目链接[D.CutandStick](http//codeforces.com/contest/1514/problem/D)
D.KillAnton(CodeforcesRound#723(Div.2)题解)xiaodangao
题目链接[D.KillAnton](http//codeforces.com/problemset/problem/1526/D)
B.StrangeDefinition(CodeforcesRound#694(Div.1)题解)xiaodangao
题目链接[B.StrangeDefinition](http//codeforces.com/contest/1470/problem/B)
F.UnusualMatrix(CodeforcesRound#697(Div.3)题解)xiaodangao
题目链接[F.UnusualMatrix](http//codeforces.com/problemset/problem/1475/F)
D.CleaningthePhone(CodeforcesRound#697(Div.3)题解)xiaodangao
题目链接[D.CleaningthePhone](http//codeforces.com/contest/1475/problem/D)
A.NezzarandBoard(CodeforcesRound#698(Div.1)题解)xiaodangao
思路发现2xy实际就是y关于x的对称操作，然后因为我们只有这一种操作，将所有元素放在一个数轴上可以发现，整体平移任意单位对于整体来说并没有影响。又因为我们发现如果原数组中有0，那么我们就可以通过这个操作来求出任意倍数的$x_i$，进一步的，我们可以求出所有$gcd(x_1,x_2,...,x_n)$的倍数的数，因此，当且仅当此时的$k$（即$kx_1$）是$gcd$倍数，才能通过该数组构成$k$。
D.MaxMedian(CodeforcesRound#703(Div.2)题解)xiaodangao
题目链接[D.MaxMedian](http//codeforces.com/contest/1486/problem/D)
1516CBabyEhabPartitionsAgain(CodeforcesRound#717(Div.2)题解)xiaodangao
题目链接[1516CBabyEhabPartitionsAgain](http//codeforces.com/contest/1516/problem/C)