BZOJ2729 [HNOI2012]排队【高精 + 组合数学】

题目链接

题解

高考数学题。。。

我们先把老师看做男生，女生插空站

如果两个老师相邻，我们把他们看做一个男生，女生插空站

对于\(n\)个男生\(m\)个女生的方案数：

\[n!m!{n + 1 \choose m}
\]

还要特判一下没有男生女生的情况

然后高精即可

#include<algorithm>

#include<iostream>

#include<cstring>

#include<cstdio>

#include<cmath>

#include<map>

#define Redge(u) for (int k = h[u],to; k; k = ed[k].nxt)

#define REP(i,n) for (int i = 1; i <= (n); i++)

#define mp(a,b) make_pair<int,int>(a,b)

#define cls(s) memset(s,0,sizeof(s))

#define cp pair<int,int>

#define LL long long int

using namespace std;

const int maxn = 100005,B = 10000,maxm = 100005,INF = 1000000000;

inline int read(){

	int out = 0,flag = 1; char c = getchar();

	while (c < 48 || c > 57){if (c == '-') flag = -1; c = getchar();}

	while (c >= 48 && c <= 57){out = (out << 3) + (out << 1) + c - 48; c = getchar();}

	return out * flag;

}

struct NUM{

	int s[4000],len;

	NUM(){cls(s); len = 0;}

	void out(){

		printf("%d",s[len]);

		for (int i = len - 1; i; i--)

			printf("%04d",s[i]);

	}

}A,C;

inline NUM operator *(const NUM& a,const int& b){

	NUM c;

	c.len = a.len;

	LL carry = 0,tmp;

	for (int i = 1; i <= a.len; i++){

		tmp = a.s[i] * b + carry;

		c.s[i] = tmp % B;

		carry = tmp / B;

	}

	while (carry) c.s[++c.len] = carry % B,carry /= B;

	return c;

}

inline NUM operator -(const NUM& a,const NUM& b){

	NUM c;

	c.len = a.len;

	int carry = 0,tmp;

	for (int i = 1; i <= a.len; i++){

		tmp = a.s[i] - b.s[i] + carry;

		if (tmp < 0) tmp += B,carry = -1;

		else carry = 0;

		c.s[i] = tmp;

	}

	while (c.len && !c.s[c.len]) c.len--;

	return c;

}

int main(){

	int n = read(),m = read();

	if (n + 3 < m || (!n && !m)){

		puts("0"); return 0;

	}

	n += 2;

	A.s[A.len = 1] = 1;

	for (int i = n; i > n - m + 1; i--)

		A = A * i;

	for (int i = n + 1; i; i--)

		A = A * i;

	n--;

	if (n + 1 >= m){

		C.s[C.len = 1] = 1;

		for (int i = n; i > n - m + 1; i--)

			C = C * i;

		for (int i = n + 1; i; i--)

			C = C * i;

		C = C * 2;

	}

	A = A - C;

	A.out();

	return 0;

}

巴特西

BZOJ2729 [HNOI2012]排队【高精 + 组合数学】

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巴特西

BZOJ2729 [HNOI2012]排队 【高精 + 组合数学】

题目链接

题解

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BZOJ2729 [HNOI2012]排队【高精 + 组合数学】