Data commit

Task/N-queens-problem/SAS/n-queens-problem.sas

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+/* Store all 92 permutations in a SAS dataset. Translation of Fortran 77 */
+data queens;
+array a{8} p1-p8;
+array s{8};
+array u{30};
+n=8;
+do i=1 to n;
+a(i)=i;
+end;
+do i=1 to 4*n-2;
+u(i)=0;
+end;
+m=0;
+i=1;
+r=2*n-1;
+goto L40;
+L30:
+s(i)=j;
+u(p)=1;
+u(q+r)=1;
+i=i+1;
+L40:
+if i>n then goto L80;
+j=i;
+L50:
+z=a(i);
+y=a(j);
+p=i-y+n;
+q=i+y-1;
+a(i)=y;
+a(j)=z;
+if u(p)=0 and u(q+r)=0 then goto L30;
+L60:
+j=j+1;
+if j<=n then goto L50;
+L70:
+j=j-1;
+if j=i then goto L90;
+z=a(i);
+a(i)=a(j);
+a(j)=z;
+goto L70;
+L80:
+m=m+1;
+output;
+L90:
+i=i-1;
+if i=0 then goto L100;
+p=i-a(i)+n;
+q=i+a(i)-1;
+j=s(i);
+u(p)=0;
+u(q+r)=0;
+goto L60;
+L100:
+put n m;
+keep p1-p8;
+run;