Problem DescriptionThere are an equation.∑0≤k1,k2,⋯km≤n∏1⩽j<m(kj1kj)%1000000007?We define that (kj1kj)kj1!kj!(kj1−kj)!. And (kj1kj)0while kj1<kj.You have to get the answer for each nand mthat given to you.For example,if n1,m3,When k10,k20,k30…
Problem DescriptionThere is a nmboard, a chess want to go to the position (n,m)from the position (1,1).The chess is able to go to position (x2,y2)from the position (x1,y1), only and if only x1,y1,x2,y2is satisfied that (x2−x1)2(y2−y1)25, x2>x1, y2>…
Description Mike wants to prepare for IMO but he doesnt know geometry, so his teacher gave him an interesting geometry problem. Lets definef([l, r]) r - l 1 to be the number of integer points in the segment [l, r] with l ≤ r (say that ). You a…
Description 求有多少种长度为 n 的序列 A,满足以下条件:1 ~ n 这 n 个数在序列中各出现了一次若第 i 个数 A[i] 的值为 i,则称 i 是稳定的。序列恰好有 m 个数是稳定的满足条件的序列可能很多,序列数对 10^97 取模。Input 第一行…
此题跟2048很相似,都是错排的问题,只不过加入组合数的知识罢了。 代码如下:
#include<cstdio>
#include<iostream>
using namespace std;
long long array[25];
int main()
{long long n,m;int i,kase;long long a,b;for(i2;i&l…
用莫队求组合数是一种常见套路
莫队求 S ( n , m ) ∑ i 0 m ( n i ) S(n,m)\sum_{i0}^m\binom n i S(n,m)∑i0m(in) S ( n , m 1 ) S(n,m1) S(n,m1) 直接做个差,然后就相当于加上 ( n i 1 ) \binom n {i1} (i1n)
求 S ( n 1 , m ) S(n1,m) S(n1,m)…
目录 1 基础知识2 模板3 工程化 1 基础知识
(一) 组合数 C n k C_n^k Cnk的计算公式, C n k n ! k ! ⋅ ( n − k ) ! C_n^k\frac{n!}{k!\cdot (n-k)!} Cnkk!⋅(n−k)!n! 故可以这样计算,
int compute_combination_n_k(…