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