11464 Even Parity

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cstdlib>
using namespace std;
const int INF = ~0U >> 1;
const int maxn = 20;
const int dx[] = {0, -1, 0, 1};
const int dy[] = {-1, 0, 1, 0};
int T, n, kase = 0;
int str[maxn][maxn], s[maxn][maxn];

void print() {
    for(int i = 1; i <= n; ++i) {
        for(int j = 1; j <= n; ++j)
            printf("%d ", s[i][j]);
        printf("\n");
    }
}

int slove(int ss) {
    int ans = 0;
    for(int i = 1; i <= n; ++i) {
        if(ss & (1 << (i - 1))) {
            if(str[1][i] == 0) {
                s[1][i] = 1;
                ++ans;
            }
        } else {
            if(str[1][i] == 1) return INF;
        }
    }
    //printf("++++\n");
    bool ok = true;
    int nx, ny;
    for(int i = 1; i < n; ++i) {
        for(int j = 1; j <= n; ++j) {
            int cnt = 0;
            for(int k = 0; k < 3; ++k) {
                nx = dx[k] + i, ny = dy[k] + j;
                cnt += s[nx][ny];
            }
            nx = i + dx[3], ny = j + dy[3];
            if(cnt == 1 || cnt == 3) { /// jishu
                if(s[nx][ny] == 0) {
                    ++ans;
                    s[nx][ny] = 1;
                }
            } else {
                //if(ss == 0) printf("%d  %d****%d  %d****%d  %d\n", i, j, dx[3], dy[3], nx, ny);
                if(s[nx][ny] == 1) {
                    ok = false;
                    goto leap;
                }
            }
        }
    }
    //if(ss == 0) print();
leap:
    if(ok) return ans;
    else return INF;
}

int main() {
    scanf("%d", &T);
    while(T--) {
        memset(str, 0, sizeof(str));
        memset(s, 0, sizeof(s));
        scanf("%d", &n);
        for(int i = 1; i <= n; ++i)
            for(int j = 1; j <= n; ++j)
                scanf("%d", &str[i][j]);
        memcpy(s, str, sizeof(str));
        //print();
        int ans = INF;
        for(int i = 0; i < (1 << n); ++i) {
            int d = slove(i);
            //printf("%d+++\n", d);
            if(ans > d) ans = d;
            memcpy(s, str, sizeof(str));
        }
        //print();
        //printf("%d----\n", ans);
        printf("Case %d: ", ++kase);
        if(ans == INF) printf("-1\n");
        else printf("%d\n", ans);
    }
    return 0;
}