hiho一下 第五十七週 高斯消元·二(高斯消元解異或方程組)

//package project1;
import java.io.*;
import java.util.*;
public class Main{
	FastScanner in;
	int[][] A;
	int[] x;
	int Major[];
	int dx[]={0,0,1,-1};
	int dy[]={1,-1,0,0};
	void Gauss(int equ,int var){
		int row,col;
		for(row=col=0;row<equ&&col<var;row++,col++){
			int max_r=row;
			for(int i=row+1;i<equ;i++){
				if(A[row][col]==1)break;
				if(A[i][col]==1){max_r=i;break;}
			}
			if(max_r!=row){
				for(int j=col;j<var+1;j++){
					int temp=A[max_r][j];
					A[max_r][j]=A[row][j];
					A[row][j]=temp;
				}
			}
			if(A[row][col]==0){
				row--;continue;
			}
			for(int i=row+1;i<equ;i++){
				if(A[i][col]==0)continue;
				for(int j=col;j<var+1;j++){
					A[i][j]^=A[row][j];
				}
			}
			Major[row]=col;
		}
		dfs_freevar(var,row-1,col-1);
	}
	void print(){
		int ans=0;
		for(int i=0;i<30;i++)
			if(x[i]==1)ans++;
		System.out.println(ans);
		for(int i=0;i<30;i++){
			if(x[i]==1){
				int xx=i/6+1,yy=i%6+1;
				System.out.println(xx+" "+yy);
			}
			
		}
		
	}
	void dfs_freevar(int n,int r,int var){
		if(r==-1||var==-1){
			print();
			return;
		}
		if(Major[r]==var){
			int y=A[r][n];
			for(int i=var+1;i<n;i++)
			{
				y^=(x[i]*A[r][i]);
			}
			x[var]=y;
			dfs_freevar(n,r-1,var-1);
		}
		else{
			for(int i=0;i<2;i++){
				x[var]=i;
				dfs_freevar(n,r,var-1);
			}
		}
		
	}
	void input(){
		in=new FastScanner(System.in);
		A=new int[35][35];
		x=new int[35];
		Major=new int[35];
		String s=new String();
		int cnt=0;
		for(int i=0;i<5;i++){
			s=in.nextLine();
			for(int j=0;j<6;j++){
				if(s.charAt(j)=='1')A[cnt++][30]=0;
				else A[cnt++][30]=1;
			}
		}
		for(int i=0;i<5;i++){
			for(int j=0;j<6;j++){
				A[i*6+j][i*6+j]=1;
				for(int k=0;k<4;k++){
					int xx=dx[k]+i,yy=dy[k]+j;
					if(xx>=0&&xx<5&&yy>=0&&yy<6){
						A[xx*6+yy][i*6+j]=1;
					}
				}	
				
			}
		}
				
		Gauss(30,30);
			
	}
	int max(int a,int b){
		if(a>b)return a;
		else return b;
	}
	int min(int a,int b){
		if(a>b)return b;
		return a;
	}
		public static void main(String args[]){
		new Main().input();
	} 
}
class FastScanner {
    BufferedReader br;
    StringTokenizer st;
    
    public FastScanner(File f) {
        try {
            br = new BufferedReader(new FileReader(f));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    public FastScanner(InputStream f) {
        br = new BufferedReader(new InputStreamReader(f));
    }

    String next() {
        while (st == null || !st.hasMoreTokens()) {
            String s = null;
            try {
                s = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (s == null)
                return null;
            st = new StringTokenizer(s);
        }
        return st.nextToken();
    }

    boolean hasMoreTokens() {
        while (st == null || !st.hasMoreTokens()) {
            String s = null;
            try {
                s = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (s == null)
                return false;
            st = new StringTokenizer(s);
        }
        return true;
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }
    String nextLine() {
    	
		String str = "";
		try {
			str = br.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return str;
	}
}