UVA 11464 Even Parity

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 20
const int INF = 0x3f3f3f3f ;
int sta;
int res[MAXN][MAXN];
int ty[MAXN][MAXN];
int N;
int getans(int sta,int cnt)
{
        int ans = cnt;
        //printf("ans = %d\n",ans);
        for (int i = 1; i < N; i++)
                for (int j = 0 ; j < N; j++)
        {
                int sum = 0;
                if (i > 1) sum += ty[i - 2][j];
                if (j > 0) sum += ty[i - 1][j - 1];
                if (j < N - 1) sum +=ty[i - 1][j + 1];
                ty[i][j] = sum % 2;
                if (ty[i][j] == 0 && res[i][j] == 1) return INF;
        }
        for (int i = 1; i < N; i++)
                for (int j = 0 ; j < N; j++)
                if (ty[i][j] != res[i][j]) ans++;
       // printf("ans =%d\n\n",ans);
        return ans;
}
int main()
{
       // freopen("sample.txt","r",stdin);
        int kase = 1 , T;
        scanf("%d",&T);
        while (T--)
        {
                scanf("%d",&N);
                for (int i = 0; i < N; i++)
                        for (int j = 0 ; j < N; j++) scanf("%d",&res[i][j]);
                int ans = INF;
                for (int s = 0 ; s < 1<<N; s++)
                {
                        bool flag = false;
                        int tmp = 0;
                        memset(ty,0,sizeof(ty));
                        for (int i = 0 ; i < N; i++)
                        {
                                if(((s & (1 << i)) == 0) && res[0][N - 1 - i])
                                {
                                        flag = true;
                                        break;
                                }
                                if ((s & (1 << i)) && res[0][N - 1 - i] == 0)
                                {
                                        tmp++;
                                        ty[0][N- 1 - i] = 1;
                                }
                                if ((s & (1 << i)) && res[0][N - 1 - i])
                                        ty[0][N - 1 -i] = 1;
                        }
                        if  (flag) continue;
                        //printf("%d\n",s);
                        //for (int i = 0; i < N ; i++) printf("%d ",ty[0][i]);
                        tmp = getans(s,tmp);
                        ans = min(ans,tmp);
                }
                if (ans == INF) ans = -1;
                printf("Case %d: %d\n",kase++,ans);
        }
        return 0;
}