Description
某中学有 n 名男同学，m 名女同学和两名老师要排队参加体检。他们排成一条直线，并且任意两名女同学不能相邻，两名老师也不能相邻，那么一共有多少种排法呢？（注意：任意两个人都是不同的）
Solution
好像必须写压位高精的QAQ
先排n名男生，插空，讨论两名老师插在两个不同的空里的情况和先排在一起再在中间插一名女生的情况
#include<iostream> #include<cstdio> #include<cstring> #include<cstdlib> typedef long long LL; using namespace std; struct Bign {static const int base=100000;static const int width=5;LL len,s[10010];Bign(){memset(s,0,sizeof(s));len=1;}Bign(int num){*this=num;}void clear(){while(len>1&&!s[len-1])len--;} Bign operator = (int num){len=0;while(num){s[len++]=num%base;num/=base;}return *this;}Bign operator + (const Bign& b) {Bign c;c.len=0;for(int i=0,g=0;g||i<max(len,b.len);i++){int x=g;if(i<b.len)x+=b.s[i];if(i<len)x+=s[i];c.s[c.len++]=x%base;g=x/base;}return c;}Bign operator * (const Bign& b){Bign c;c.len=len+b.len;for(int i=0;i<len;i++){for(int j=0;j<b.len;j++){c.s[i+j]+=s[i]*b.s[j];}}for(int i=0;i<c.len;i++){c.s[i+1]+=c.s[i]/base;c.s[i]%=base;}c.clear();return c;}Bign operator * (const int& b){Bign c;c.len=0;for(int i=0,g=0;g||i<len;i++){int x;if(i<len)x=s[i]*b+g;else x=g;c.s[c.len++]=x%base;g=x/base;}return c;}void print() {string res;printf("%d",s[len-1]);for(int i=len-2;i>=0;i--)printf("%05d",s[i]);} }; Bign A(int x,int y) {if(x>y)return Bign();Bign c=1;for(int i=y-x+1;i<=y;i++)c=c*i;return c; } int n,m; int main() {scanf("%d%d",&n,&m);Bign ans;ans=A(n,n)*(A(2,n+1)*A(m,n+3)+A(1,n+1)*A(2,2)*A(1,m)*A(m-1,n+2)); ans.print();return 0; }
