标签:des style os io for ar cti div
The binomial coefficient C(m,n) is defined asm! C(m,n) = -------- n!(m-n)!
10 5 14 9 93 45 84 59 145 95 143 92 995 487 996 488 2000 1000 1999 999 9998 4999 9996 4998
0.12587 505606.46055 1.28223 0.48996 2.00000 3.99960
唯一分解定理:
#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<limits.h> #include<vector> #include<cmath> typedef long long LL; typedef unsigned long long ULL; using namespace std; const int maxn=10005; int e[maxn]; int p,q,r,s; int visit[maxn]; vector<int>prime; void is_prime(int n) { int m=sqrt(n+0.5); memset(visit,0,sizeof(visit)); for(int i=2;i<=m;i++) { for(int j=i*i;j<=n;j+=i) visit[j]=1; } } void get_prime(int n) { for(int i=2;i<=n;i++) { if(!visit[i]) prime.push_back(i); } } void add_integer(int n,int d) { for(int i=0;i<prime.size();i++) { while(n%prime[i]==0) { n/=prime[i]; e[i]+=d; } if(n==1) break; } } void add_factorial(int n,int d) { for(int i=1;i<=n;i++) add_integer(i,d); } int main() { is_prime(maxn-1); get_prime(maxn-1); while(cin>>p>>q>>r>>s) { memset(e,0,sizeof(e)); add_factorial(p,1); add_factorial(q,-1); add_factorial(p-q,-1); add_factorial(r,-1); add_factorial(s,1); add_factorial(r-s,1); double ans=1.0; for(int i=0;i<prime.size();i++) ans*=pow(prime[i],e[i]); printf("%.5f\n",ans); } return 0; }
还有一种方法:
#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<limits.h> typedef long long LL; typedef unsigned long long ULL; using namespace std; int p,q,r,s; int main() { while(~scanf("%d%d%d%d",&p,&q,&r,&s)) { if(p-q<q)//q和p-q中较大值的阶乘和p的阶乘消去 q=p-q; if(r-s<s) s=r-s; double ans=1.0; for(int i=1;i<=q||i<=s;i++) { if(i<=q) ans=ans*(p-q+i)/i; if(i<=s) ans=ans/(r-s+i)*i; } printf("%.5f\n",ans); } return 0; }
UVA 10375 Choose and divide(数论),布布扣,bubuko.com
UVA 10375 Choose and divide(数论)
标签:des style os io for ar cti div
原文地址:http://blog.csdn.net/u013582254/article/details/38668995