delete pics to save space

1.5431.cpp

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