There are n cards (n is even) in the deck. Each card has a positive integer written on it. n / 2 people will play new card game. At the beginning of the game each player gets two cards, each card is given to exactly one player. Find the way to distri…

Content 有一个长度为 \(n\) 的数组 \(a_1,a_2,a_3,...,a_n\),试在其中找到 \(\dfrac{n}{2}\) 对数,使得每个数对的元素的和都相等. 数据范围:\(2\leqslant n\leqslant 100,1\leqslant a_i\leqslant 100\).\(n\) 保证是偶数. Solution 我们先算出这些数的总和 \(s\),然后每个数对的和就是 \(\dfrac{s}{\dfrac{n}{2}}=\dfrac{2s}{n}\),又由…

题目链接:Cards 听说这道题是染色问题的入门题,于是就去学了一下\(Bunside\)引理和\(P\acute{o}lya\)定理(其实还是没有懂),回来写这道题. 由于题目中保证"任意多次洗牌都可用这\(m\)种洗牌法中的一种代替",于是有了封闭性. 结合律显然成立. 题目中还保证了"对每种洗牌法,都存在一种洗牌法使得能回到原状态",逆元也有了. 只剩下一个单位元,我们手动补上.单位元就是不洗牌. 所以所有的洗牌方案构成了一个置换群.于是就可以用$Bunsid…

E. Vladik and cards time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Vladik was bored on his way home and decided to play the following game. He took n cards and put them in a row in front…

1004: [HNOI2008]Cards Description 小春现在很清闲,面对书桌上的N张牌,他决定给每张染色,目前小春只有3种颜色:红色,蓝色,绿色.他询问Sun有 多少种染色方案,Sun很快就给出了答案.进一步,小春要求染出Sr张红色,Sb张蓝色,Sg张绝色.他又询问有多少种方 案,Sun想了一下,又给出了正确答案. 最后小春发明了M种不同的洗牌法,这里他又问Sun有多少种不同的染色方案. 两种染色方法相同当且仅当其中一种可以通过任意的洗牌法(即可以使用多种洗牌法,而每种方法可以使…

C. Hongcow Buys a Deck of Cards time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output One day, Hongcow goes to the store and sees a brand new deck of n special cards. Each individual card is eit…

题目链接: 传送门 Little Elephant and Cards time limit per test:2 second     memory limit per test:256 megabytes Description The Little Elephant loves to play with color cards. He has n cards, each has exactly two colors (the color of the front side and the…

题目链接: 传送门 Invitation Cards Time Limit: 5000MS     Memory Limit: 32768 K Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They want to propagate theater and, mo…

E. George and Cards   George is a cat, so he loves playing very much. Vitaly put n cards in a row in front of George. Each card has one integer written on it. All cards had distinct numbers written on them. Let's number the cards from the left to the…

Soldier and Cards 题目: Description Two bored soldiers are playing card war. Their card deck consists of exactly n cards, numbered from 1 to n, all values are different. They divide cards between them in some manner, it's possible that they have differ…