bzoj 1002[FJOI2007]轮状病毒

 1 /*
 2  * Problem: BZOJ 1002 
 3  * Author:  SHJWUDP
 4  * Created Time:  2015/4/15 星期三 19:24:14
 5  * File Name: Main.java
 6  * State: Accepted
 7  * Memo: Matrix-Tree
 8  */
 9 import java.util.*;
10 import java.io.*;
11 import java.math.*;
12 
13 public class Main {
14     public static void main(String args[]) throws IOException {
15         InputStream inputStream = System.in;
16         OutputStream outputStream = System.out;
17         InputReader in = new InputReader(inputStream);
18         PrintWriter out = new PrintWriter(outputStream);
19 
20         TaskA solver = new TaskA();
21         solver.solve(in, out);
22         out.close();
23     }
24 }
25 
26 class TaskA {
27     public void solve(InputReader in, PrintWriter out) {
28         int n=in.nextInt();
29         if(n<=1) {
30             out.print(1+"\n");
31             return ;
32         }
33         int[][] D=new int[n+1][n+1];
34         int[][] A=new int[n+1][n+1];
35         D[n][n]=n;
36         for(int i=0; i<n; i++) D[i][i]=3;
37         for(int i=0; i<n; i++) {
38             A[i][n]=A[n][i]=1;
39             int r=(i+1)%n;
40             A[i][r]=A[r][i]=1;
41         }
42 
43         BigInteger[][] C=new BigInteger[n+1][n+1];
44         for(int i=0; i<=n; i++) {
45             for(int j=0; j<=n; j++) {
46                 C[i][j]=BigInteger.valueOf(D[i][j]-A[i][j]);
47             }
48         }
49 
50         //计算C的m-1阶行列式 (m=n+1)
51         BigInteger ans=BigInteger.ONE;
52         for(int i=0; i<n; i++) {
53             for(int j=i+1; j<n; j++) while(C[j][i]!=BigInteger.ZERO) {
54                 BigInteger t=C[i][i].divide(C[j][i]);
55                 for(int k=i; k<n; k++) {
56                     C[i][k]=C[i][k].subtract(C[j][k].multiply(t));
57                 }
58                 for(int k=i; k<n; k++) {
59                     BigInteger tmp=C[i][k];
60                     C[i][k]=C[j][k];
61                     C[j][k]=tmp;
62                 }
63                 ans=ans.negate();
64             }
65             ans=ans.multiply(C[i][i]);
66         }
67         if(ans.compareTo(BigInteger.ZERO)<0) ans=ans.negate();
68         out.print(ans+"\n");
69     }
70 }
71 
72 class InputReader {
73     public BufferedReader reader;
74     public StringTokenizer tokenizer;
75 
76     public InputReader(InputStream stream) {
77         reader = new BufferedReader(new InputStreamReader(stream), 32768);
78         tokenizer = null;
79     }
80 
81     public String next() {
82         while(tokenizer == null || !tokenizer.hasMoreTokens()) {
83             try {
84                 tokenizer = new StringTokenizer(reader.readLine());
85             } catch (IOException e) {
86                 throw new RuntimeException(e);
87             }
88         }
89         return tokenizer.nextToken();
90     }
91 
92     public int nextInt() {
93         return Integer.parseInt(next());
94     }
95 
96     public BigInteger nextBigInt() {
97         return new BigInteger(next());
98     }
99 }