1282 时钟(最小表示法+hash)

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 #define INF 0x3f3f3f3f
 4 #define LL long long
 5 #define MX 505
 6 
 7 const int hash_ = 133331;
 8 
 9 int n, m, p;
10 int ans;
11 int ke[MX];
12 int cha[MX];
13 map<LL,int> zz;
14 
15 int get_min(int *s, int len) //返回最小表示法的始端
16 {
17     int i = 0, j = 1, k = 0;
18     while(i<len && j<len && k<len)
19     {
20         int t = s[(i+k)%len]-s[(j+k)%len];
21         if (!t) k++;
22         else
23         {
24             if (t>0) i += k+1;
25             else j += k+1;
26             if (i==j) j++;
27             k = 0;
28         }
29     }
30     return i<j?i:j;
31 }
32 
33 void calc()
34 {
35     sort(ke,ke+m);
36     for (int i=1;i<m;i++)
37         cha[i-1] = ke[i]-ke[i-1];
38     cha[m-1] = ke[0]+p-ke[m-1];
39     int dex= get_min(cha,m);
40 
41     LL has=0, quan =1;
42     for (int i=0;i<m;i++)
43     {
44         has += cha[(dex+i)%m]*quan;
45         quan*= hash_;
46     }
47     ans+=zz[has];
48     zz[has]++;
49 }
50 
51 int main()
52 {
53     scanf("%d%d%d",&n,&m,&p);
54     ans = 0;
55     for (int i=0;i<n;i++)
56     {
57         for (int j=0;j<m;j++)
58             scanf("%d",&ke[j]);
59         calc();
60     }
61     printf("%d\n",ans);
62     return 0;
63 }