用system verilog constrain random求解八皇后问题

class Queens;
rand int Q[8];
constraint Qi{
foreach(Q[i])
Q[i] inside {[1:8]};
}
constraint Qi_n_Qj{
foreach(Q[i])
foreach(Q[j])
if(i!=j){
Q[i] != Q[j];
!((Q[i]-Q[j]) inside {(i-j), (j-i)});
}
}
endclass
program Eight_Queens;
parameter N=800; //loop times
int Array1[N][8]; 
int Result[N][8]; //default is zero
int m = 1;
int sum = 0;
int midvalue;
initial begin
Queens qc = new();
for(int i=0;i<N;i++) begin
qc.randomize();	//randomize Q
foreach(qc.Q[j]) Array1[i][j]=qc.Q[j];
if(i == 0) Result[0] = Array1[i];
//remove duplicate content,from the second 
if(i>0) begin
for(int k=0;k<i;k++) begin
for(int j=0;j<8;j++) begin 
//if sum not equal to zero,two line are different,the abs of Array1[k][j] minus Array1[i][j]
if(Array1[i][j]>Array1[k][j]) midvalue = Array1[i][j]-Array1[k][j];
else midvalue = Array1[k][j]-Array1[i][j];
sum = sum + midvalue;
end
if(k != (i-1)) begin
if(sum == 0) break;  //equal to some line,$break
else sum = 0;	      //rejudge next line
end
if(k == (i-1)) begin //judge equal to provious line or not
if(sum == 0) break;
end
end
if(!(sum == 0)) begin
Result[m] = Array1[i];
m = m+1;
sum = 0;
end
end 
end
foreach(Result[i]) begin
//remove usless line,the answer can't be start with 0
if(!(Result[i][0] == 0))	
$display("qc.Q is %p",Result[i]);
end
end
endprogram

使用如下命令（如果没有安装vcs，可以在这个网站注册账号，选择编译器为synopsys vcs，注册需要教育邮箱）。

vcs -full64 Eight_Queens.sv -sverilog

然后会生成simv可执行文件，执行

./simv

当N=8时，结果如下：

当N=80是，结果如下