uvalive 11464

题意：怎么使最少的０变成１让原矩阵的每个数的上下左右之和为偶数

思路：枚举第一行就可以确定所有的状态

package text;

import java.awt.List;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Map;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) throws IOException {
        InputReader cin = new InputReader(System.in);
        int t;
        int n;
        int cube[][] = new int[50][50];
        int now[][] = new int[50][50];
        t = cin.nextInt();
        for(int p = 1;p<=t;p++){
            int ans = -1;
            n = cin.nextInt();
            for(int i = 1;i<=n;i++)
                for(int j = 1;j<=n;j++)
                    cube[i][j] = cin.nextInt();
            for(int i = 0;i<1<<n;i++) {
                int tmp = i;
                int tmpans = 0;
                for(int j = 1;j<=n;j++) {
                    now[1][j] = tmp&1;
                    tmp/=2;
                }
                boolean flag = true;
                for(int j = 1;j<=n;j++)
                    if(cube[1][j]==0&&now[1][j]==1)
                        tmpans++;
                    else if(cube[1][j]==1&&now[1][j]==0)
                        flag = false;
                for(int j = 2;j<=n;j++)
                    for(int k = 1;k<=n;k++)
                            now[j][k] = 0;
                for(int j = 2;j<=n;j++) {
                    for(int k = 1;k<=n;k++) {
                        int s = 0,nowj = j-1;
                        if(nowj>=2) s+=now[nowj-1][k];
                        if(k>=2) s+=now[nowj][k-1];
                        if(k<n) s+=now[nowj][k+1];
                        now[j][k] = s%2;
                        if(now[j][k]==0&&cube[j][k]==1) {
                            flag = false;
                            break;
                        }
                        if(now[j][k]==1&&cube[j][k]==0)
                            tmpans++;
                    }
                    if(!flag)
                        break;
                }
                if(flag&&(tmpans<ans||ans==-1))
                    ans = tmpans;
            }
            if(ans==-1)
                System.out.printf("Case %d: -1
",p);
            else 
                System.out.printf("Case %d: %d
",p,ans);
        }
    }
}
class InputReader {      
    public BufferedReader reader;      
    public StringTokenizer tokenizer;      
      
    public InputReader(InputStream stream) {      
        reader = new BufferedReader(new InputStreamReader(stream), 32768);      
        tokenizer = new StringTokenizer("");      
    }      
    
    
    private void eat(String s) {      
        tokenizer = new StringTokenizer(s);      
    }      
      
    public String nextLine() {       
        try {      
            return reader.readLine();      
        } catch (Exception e) {      
            return null;      
        }      
    }      
      
    public boolean hasNext() {      
        while (!tokenizer.hasMoreTokens()) {      
            String s = nextLine();      
            if (s == null)      
                return false;      
            eat(s);      
        }      
        return true;      
    }      
      
    public String next() {      
        hasNext();      
        return tokenizer.nextToken();      
    }      
      
    public int nextInt() {      
        return Integer.parseInt(next());      
    }      
      
    public int[] nextInts(int n) {      
        int[] nums = new int[n];      
        for (int i = 0; i < n; i++) {      
            nums[i] = nextInt();      
        }      
        return nums;      
    }      
      
    public long nextLong() {      
        return Long.parseLong(next());      
    }      
      
    public double nextDouble() {      
        return Double.parseDouble(next());      
    }      
      
    public BigInteger nextBigInteger() {      
        return new BigInteger(next());      
    }      
}