BZOJ2134 单选错位

 1 /**************************************************************
 2     Problem: 2134
 3     User: rausen
 4     Language: C++
 5     Result: Accepted
 6     Time:1292 ms
 7     Memory:78932 kb
 8 ****************************************************************/
 9  
10 #include <cstdio>
11 #include <cmath>
12  
13 using namespace std;
14 typedef double lf;
15 typedef long long ll;
16 const int N = 10000005;
17 const ll Mod = 100000001;
18 ll n, a, b, c, d[N];
19  
20 inline int read() {
21     int x = 0;
22     char ch = getchar();
23     while (ch < ‘0‘ || ‘9‘ < ch)
24         ch = getchar();
25     while (‘0‘ <= ch && ch <= ‘9‘) {
26         x = x * 10 + ch - ‘0‘;
27         ch = getchar();
28     }
29     return x;
30 }
31  
32 int main() {
33     int i;
34     n = read(), a = read(), b = read(), c = read();
35     for (d[1] = read(), i = 2; i <= n; ++i)
36         d[i] = (d[i - 1] * a + b) % Mod;
37     for (i = 1; i <= n; ++i)
38         d[i] = (d[i] % c) + 1;
39     d[n + 1] = d[1];
40     lf ans = 0;
41     for (i = 1; i <= n; ++i)
42         if (d[i] <= d[i + 1])
43             ans += (lf) 1.0 / d[i + 1];
44         else
45             ans += (lf) 1.0 / d[i];
46     printf("%.3lf", ans);
47     return 0;
48 }