Coldfresh的博客

对于求C(n,m) 1.如果是对于小范围内的n和m（不是很难）就不说了 差不多用java的大数就可以了 2.当n在1e10^5范围左右，往往是会有取模，设这个数为mod（往往mod为质数，这个很重要）。 既然是组合数，就免不了有阶乘的部分， n 的范围在10^5的数量级，所以完全可以线性扫一遍，用一个fac数组存i的阶乘对mod取模即可， 但是对于除法取模，必须得用到逆元，所以还是需要去

Giant chess is quite common in Geraldion. We will not delve into the rules of the game, we’ll just say that the game takes place on an h × w field, and it is painted in two colors, but not like in ches

Recently, Mr. Big recieved n owers from his fans. He wants to recolor those owers with m colors. The owers are put in a line. It is not allowed to color any adjacent owers with the same color. Flowers

给定一个多项式(ax + by)^k，请求出多项式展开后x^n y^m项的系数。输入描述 Input Description 共一行，包含 5 个整数，分别为a，b，k，n，m，每两个整数之间用一个空格隔开。输出描述 Output Description 输出共 1 行，包含一个整数，表示所求的系数，这个系数可能很大，输出对10007 取模后的结果。样例输入 Sample Inpu...

On the way to the next secret treasure hiding place, the mathematician discovered a cave unknown to the map. The mathematician entered the cave because it is there. Somewhere deep in the cave, she foun