数论/暴力 Codeforces Round #305 (Div. 2) C. Mike and Frog

 1 /*
 2     数论/暴力：找出第一次到a1,a2的次数，再找到完整周期p1,p2，然后以2*m为范围
 3                 t1,t2为各自起点开始“赛跑”，谁落后谁加一个周期，等到t1 == t2结束
 4     详细解释：http://blog.csdn.net/u014357885/article/details/46044287
 5 */
 6 #include <cstdio>
 7 #include <algorithm>
 8 #include <cstring>
 9 #include <iostream>
10 using namespace std;
11 
12 typedef long long ll;
13 
14 const int MAXN = 1e3 + 10;
15 const int INF = 0x3f3f3f3f;
16 
17 int main(void)        //Codeforces Round #305 (Div. 2) C. Mike and Frog
18 {
19     int m;
20     ll h1, a1, x1, y1, h2, a2, x2, y2;
21     while (scanf ("%d%I64d%I64d%I64d%I64d%I64d%I64d%I64d%I64d", &m, &h1, &a1, &x1, &y1, &h2, &a2, &x2, &y2) == 9)
22     {
23         ll t1 = -1, t2 = -1, p1 = -1, p2 = -1;
24         for (int i=1; i<=m; ++i)                //get t1, p1
25         {
26             h1 = (h1 * x1 + y1) % m;
27             if (h1 == a1)    {t1 = i; break;}
28         }
29         if (t1 == -1)    {puts ("-1"); continue;}
30         for (int i=1; i<=m; ++i)
31         {
32             h1 = (h1 * x1 + y1) % m;
33             if (h1 == a1)    {p1 = i; break;}
34         }
35 
36         for (int i=1; i<=m; ++i)                //get t2, p2
37         {
38             h2 = (h2 * x2 + y2) % m;
39             if (h2 == a2)    {t2 = i; break;}
40         }
41         if (t2 == -1)    {puts ("-1"); continue;}
42         for (int i=1; i<=m; ++i)
43         {
44             h2 = (h2 * x2 + y2) % m;
45             if (h2 == a2)    {p2 = i; break;}
46         }
47 
48         bool ok = false;                        //get t1 == t2
49         for (int i=1; i<=2*m; ++i)
50         {
51             if (t1 == t2)    {ok = true; printf ("%I64d\n", t1);    break;}
52             if (t1 < t2)    t1 += p1;
53             else    t2 += p2;
54         }
55         if (!ok)    puts ("-1");
56     }
57 
58     return 0;
59 }
60 
61 /*
62 5
63 4 2
64 1 1
65 0 1
66 2 3
67 1023
68 1 2
69 1 0
70 1 2
71 1 1
72 */