% A 是邻接矩阵,可以由用户输入
A = [0 0 1 0 0 0 0 0 0
0 0 0 0 0 0 1 0 0
0 0 0 0 1 0 0 0 0
0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 1 0
0 0 0 1 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0
];
I=eye(size(A));
R=A+I;
k=0;
while 1
Rnew=R*(A+I)>0;
if isequal(R,Rnew);
Rnew
k=k+1
break;
end
R=Rnew;
k=k+1;
end