2186: [Sdoi2008]沙拉公主的困惑 线性筛素数+欧拉函数+乘法逆元

Orz题解
数组开小了坑死人啊卧槽！

#include<iostream>#include<cstdio>#define MAXN 10000000#define ll long long using namespace std;int fac[10000005],inv[10000005],ans[10000005];int n,m,T,R,cnt;bool flag[10000005];int prime[1000005];inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline void prepare(){    for (int i=2;i<=MAXN;i++)    {        if (!flag[i]) prime[++cnt]=i;        for (int j=1;i*prime[j]<=MAXN&&j<=cnt;j++)        {            flag[i*prime[j]]=1;            if (i%prime[j]==0) break;        }    }    fac[1]=1;    for (int i=2;i<=MAXN;i++) fac[i]=(ll)fac[i-1]*i%R;    inv[1]=1;    for (int i=2;i<=MAXN;i++)         if (i<R) inv[i]=R-(ll)R/i*inv[R%i]%R; else break;    ans[1]=1;    for (int i=2;i<=MAXN;i++)    {        ans[i]=ans[i-1];        if (!flag[i]) ans[i]=(ll)ans[i]*(i-1)%R*inv[i%R]%R;    }}int main(){    T=read(); R=read();    prepare();    while (T--)    {        n=read(); m=read();        printf("%d\n",(ll)fac[n]*ans[m]%R);    }    return 0;}