[bzoj2186] [Sdoi2008]沙拉公主的困惑

　　膜了半天sxt和网上题解。。。

　　http://www.cnblogs.com/BLADEVIL/p/3490321.html

#include<cstdio>
#include<iostream>
#include<cstring>
#define ll long long
using namespace std;
const int maxn=10023333,mx=1e7;
int p[maxn],pnum;
int jc[maxn],f[maxn];
bool gg[maxn];
int i,j,k,n,m,modd;
 
int ra;char rx;
inline int read(){
    rx=getchar(),ra=0;
    while(rx<'0'||rx>'9')rx=getchar();
    while(rx>='0'&&rx<='9')ra*=10,ra+=rx-48,rx=getchar();return ra;
}
 
inline int poi(int a,int b){
    int c=1;
    while(b){
        if(b&1)c=1ll*c*a%modd;
        b>>=1,a=1ll*a*a%modd;
    }return c;
}
inline void getp(){
    register int i,j;
    for(i=2;i<=mx;i++){
        if(!gg[i])p[++pnum]=i;
        for(j=1;j<=pnum&&1ll*p[j]*i<=mx;j++){
            gg[p[j]*i]=1;
            if(!i%p[j])break;
        }
    }
}
inline void getphi(){
    f[1]=1;
    for(register int i=2;i<=mx;i++)if(!gg[i])f[i]=1ll*f[i-1]*(i-1)%modd;
    else f[i]=1ll*f[i-1]*i%modd;
}
int main(){int t;
    t=read(),modd=read();
    getp(),
    getphi();
    for(i=jc[0]=1;i<=mx;i++)jc[i]=1ll*jc[i-1]*i%modd;
    while(t--){
        n=read(),m=read();
        printf("%lld
",1ll*f[m]*jc[n]%modd*poi(jc[m],modd-2)%modd);
    }
}