65 lines
1.2 KiB
C++
65 lines
1.2 KiB
C++
#include<cstdio>
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#include<cstring>
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#include<algorithm>
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#include<cassert>
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using namespace std;
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typedef long long LL;
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struct char_reader
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{
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FILE* f;
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char *buf,*p1,*p2;
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int size;
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char_reader(FILE* fin,int bufsize=100000)
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{
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assert(bufsize>0);
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f=fin;
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size=bufsize;
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p1=p2=0;
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buf=new char[bufsize];
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}
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inline int operator()()
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{
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return p1==p2&&(p2=(p1=buf)+fread(buf,1,size,f),p1==p2)?EOF:*p1++;
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}
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};
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char_reader gch(stdin);
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inline void read(LL& t)
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{
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t=0; bool f=false; char ch;
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while(ch=gch(),!((ch>='0'&&ch<='9')||ch=='-'));
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if(ch=='-') f=true,ch=gch();
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t=ch-'0';
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while(ch=gch(),ch>='0'&&ch<='9') t=t*10+ch-'0';
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if(f) t=-t;
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}
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const int maxn=5e6+5;
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LL n,p,k,a[maxn],s[maxn];
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LL ksm(LL a,LL b)
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{
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LL res=1;
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for(;b;b>>=1,a=a*a%p) b&1?res=res*a%p:0;
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return res;
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}
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int main()
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{
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#ifdef local
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// freopen("pro.in","r",stdin);
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freopen("testdata.in","r",stdin);
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#endif
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read(n); read(p); read(k);
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for(int i=1;i<=n;i++) read(a[i]);
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s[0]=1;
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for(int i=1;i<=n;i++) s[i]=s[i-1]*a[i]%p;
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s[n]=ksm(s[n],p-2);
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LL res,d=ksm(k,p-2);
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k=ksm(k,n);
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res=k*ksm(a[n],p-2)%p;
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for(int i=n-1;i>=1;i--)
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{
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s[i]=s[i+1]*a[i+1]%p;
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k=k*d%p;
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res=(res+k*s[i-1]%p*s[i]%p)%p;
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}
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printf("%lld\n",res);
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return 0;
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} |