UVa 11464 Even Parity

 1 #include<iostream>  
 2 #include<cstdio>  
 3 #include<cstring> 
 4 #include <cmath> 
 5 #include<stack>
 6 #include<vector>
 7 #include<map> 
 8 #include<set>
 9 #include<queue> 
10 #include<algorithm>  
11 using namespace std;
12 
13 typedef long long LL;
14 const int INF = (1<<30)-1;
15 const int mod=1000000007;
16 const int maxn=1000005;
17 
18 int n;
19 int a[55][55];
20 int b[55][55];
21 int ans;
22 
23 int solve(int s){
24     memset(b,0,sizeof(b));
25     for(int c = 0; c < n;c++){
26         if( s & (1<<c)) b[0][c] = 1;
27         else if(a[0][c] == 1) return INF;
28     }
29     
30     for(int r = 1;r < n;r++){
31         for(int c = 0;c < n;c++){
32             int sum = 0;
33             if(r > 1) sum += b[r-2][c];
34             if(c < n-1) sum += b[r-1][c+1];
35             if(c > 0) sum += b[r-1][c-1];
36             b[r][c] = sum % 2;
37             if(a[r][c] == 1 && b[r][c] == 0) return INF;
38         }
39     }
40     int cnt = 0;
41     for(int i = 0;i < n;i++){
42         for(int j = 0;j < n;j++){
43             if(a[i][j] != b[i][j]) cnt++;
44         }
45     }
46     return cnt;
47 }
48 
49 int main(){
50     int T;
51     scanf("%d",&T);
52     int kase = 0;
53     while(T--){
54         memset(a,0,sizeof(a));
55         scanf("%d",&n);
56         for(int i=0;i<n;i++)
57          for(int j=0;j<n;j++) scanf("%d",&a[i][j]);
58          
59          ans = INF;
60          for(int s = 0;s < (1<<n); s++) ans = min(ans,solve(s));
61          
62          if(ans == INF) ans = -1;
63          printf("Case %d: %d\n",++kase,ans);
64     }
65     return 0;
66 }