BZOJ2134: 单选错位

#include<cstdio>

#include<cstdlib>

#include<cmath>

#include<cstring>

#include<algorithm>

#include<iostream>

#include<vector>

#include<map>

#include<set>

#include<queue>

#include<string>

#define inf 1000000000

#define maxn 10000000+5

#define maxm 500+100

#define eps 1e-10

#define ll long long

#define pa pair<int,int>

#define for0(i,n) for(int i=0;i<=(n);i++)

#define for1(i,n) for(int i=1;i<=(n);i++)

#define for2(i,x,y) for(int i=(x);i<=(y);i++)

#define for3(i,x,y) for(int i=(x);i>=(y);i--)

#define mod 100000001

using namespace std;

inline ll read()

{

ll x=0,f=1;char ch=getchar();

while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}

while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}

return x*f;

}
ll n,a,b,c,d[maxn];

int main()

{

freopen("input.txt","r",stdin);

freopen("output.txt","w",stdout);

n=read();a=read();b=read();c=read();d[1]=read();
for2(i,2,n)d[i]=(d[i-1]*a+b)%mod;
for1(i,n)d[i]=(d[i]%c)+1;d[n+1]=d[1];
double ans=0;
for1(i,n)
if(d[i+1]>=d[i])ans+=1.0/(double)d[i+1];
else ans+=1.0/(double)d[i];
printf("%.3f\n",ans);

return 0;

}