poj 1830 高斯消元

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <stack>
 5 #include <queue>
 6 #include <map>
 7 #include <algorithm>
 8 #include <vector>
 9 #include <cstdlib>
10 
11 using namespace std;
12 
13 const int maxn = 1000005;
14 
15 typedef long long LL;
16 
17 int A[35][35];
18 
19 int gauss(int m,int n) //m个方程,n个变量
20 {
21     int i=0,j=0,k,r,u;
22     while(i < m && j <n ){ //当前处理i个方程j个变量
23         r = i;
24         for(k = i;k < m;k++){
25             if(A[k][j]){
26                 r = k;
27                 break;
28             }
29         }
30         if(A[r][j]){
31             if(r != i){
32                 for(k = 0;k <= n;k++) swap(A[r][k],A[i][k]);
33             }
34             for(u = i+1;u < m;u++){
35                 if(A[u][j]) for(k = i;k <= n;k++) A[u][k] ^= A[i][k];
36             }
37             i++;
38         }
39         j++;
40 
41     }
42     for(j = i;j<n;j++){
43         if(A[j][n]) return -1;
44     }
45     return n-i;
46 }
47 
48 int main()
49 {
50    int t;
51    scanf("%d",&t);
52    int s[35],e[35];
53    while(t--){
54         memset(A,0,sizeof(A));
55         memset(s,0,sizeof(s));
56         memset(e,0,sizeof(e));
57         int n;
58         scanf("%d",&n);
59         for(int i=0;i<n;i++){
60             scanf("%d",&s[i]);
61         }
62         for(int i=0;i<n;i++){
63             scanf("%d",&e[i]);
64         }
65         for(int i=0;i<n;i++){
66             if(s[i] != e[i])
67                 A[i][n] =1;
68             A[i][i] = 1;
69         }
70         int a,b;
71         while(scanf("%d%d",&a,&b)&&a+b){
72             a--;
73             b--;
74             A[b][a] = 1;
75         }
76         int ans = gauss(n,n);
77         if(ans == -1) puts("Oh,it‘s impossible~!!");
78         else printf("%d\n",1<<ans);
79 
80    }
81     return 0;
82 }