摘要:
一个包含四个点的完全图,可以在任意节点出发,可以在任意节点结束,给出每个点被经过的次数,求有多少种合法的遍历序列。如果两个序列至少有一位是不同的,则认为它们不相同。 Input Sample Output 题意:给a个A,b个B,c个C,d个D,求有少种排列,使得相邻的两个不同。 思路:用容斥来做, 阅读全文
摘要:
As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them: Yuta ha 阅读全文
摘要:
A thief made his way to a shop. As usual he has his lucky knapsack with him. The knapsack can contain k objects. There are n kinds of products in the 阅读全文