uva 684 Integral Determinant 行列式求值

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 int n;
 6 int a[35][35];
 7 void determinant()
 8 {
 9     int cnt = 0;
10     int ans = 1;
11     for(int i = 1; i <= n; i++)
12     {
13         for(int j = i+1; j <= n; j++)
14         {
15             int x, y;
16             x = i, y = j;
17             while(a[y][i])
18             {
19                 int t = a[x][i] / a[y][i];
20                 for(int k = 1; k <= n; k++)
21                 {
22                     a[x][k] = a[x][k] - a[y][k]*t;
23                 }
24                 swap(x, y);
25             }
26             if(x != i)
27             {
28                 for(int k = 1; k <= n; k++)
29                 {
30                     swap(a[x][k], a[y][k]);
31                 }
32                 cnt ^= 1;
33             }
34         }
35         if(a[i][i] == 0)
36         {
37             ans = 0; break;
38         }
39         else ans *= a[i][i];
40     }
41     if(cnt) ans *= -1;
42     printf("%d\n", ans);
43 }
44 int main() 
45 {
46    // freopen("in.txt", "r", stdin);
47     while(scanf("%d", &n))
48     {
49         if(n == 0)
50         {
51             printf("*\n"); 
52             break;
53         }
54         for(int i = 1; i <= n; i++)
55         {
56             for(int j = 1; j <= n; j++)
57             {
58                 scanf("%d", &a[i][j]);
59             }
60         }
61         determinant();
62     }
63     return 0;
64 }