#include <iostream>

using std::cout;

using std::endl;

int n[5][5];

int init()

…{

n[0][0]=1;

n[0][1]=1;

n[0][2]=1;

n[0][3]=1;

n[0][4]=0;

n[1][0]=1;

n[1][1]=0;

n[1][2]=1;

n[1][3]=1;

n[1][4]=1;

n[2][0]=1;

n[2][1]=1;

n[2][2]=1;

n[2][3]=0;

n[2][4]=1;

n[3][0]=0;

n[3][1]=1;

n[3][2]=0;

n[3][3]=0;

n[3][4]=0;

n[4][0]=0;

n[4][1]=1;

n[4][2]=1;

n[4][3]=1;

n[4][4]=1;

return 0;

}

int find(int x,int y)

…{

cout<<x<<“\t“<<y<<endl;

if(x==4&&y==4)

…{

cout<<endl;

return 1;

}

else if(n[x][y]==0||x>4||y>4||x<0||y<0)

…{

return 0;

}

n[x][y]=0;

return find(x,y+1)+find(x+1,y);

}

int main(void)

…{

init();

int r = find(0,0);

cout<<r<<endl;

return 0;

}

#endregion

#include <iostream>

using std::cout;

using std::endl;

static int N;

static int ResultIsZeroDFS(int n, int total, int last)

…{

const int current = n+1;

int sub = total+last;

if( n == N )

…{

return (total+last == 0);

}

else

…{

int result = ResultIsZeroDFS(current, total, last*10+current)+

ResultIsZeroDFS(current, total+last, current)+

ResultIsZeroDFS(current, total-last, current);

return result;

}

}

int ResultIsZero(int n)

…{

N = n;

return ResultIsZeroDFS(1, 0, 1);

}

int main(void)

…{

cout<<ResultIsZero(8);

return 0;

}

#endregion