tasks a-s

Task/N-queens-problem/Perl-6/n-queens-problem.pl6

@@ -0,0 +1,30 @@
+sub MAIN($N = 8) {
+    sub collision(@field, $row) {
+        for ^$row -> $i {
+            my $distance = @field[$i] - @field[$row];
+            return 1 if $distance == any(0, $row - $i, $i - $row);
+        }
+        0;
+    }
+    sub search(@field is rw, $row) {
+        if $row == $N {
+            return @field;
+        } else {
+            for ^$N -> $i {
+                @field[$row] = $i;
+                if !collision(@field, $row) {
+                    my @r = search(@field, $row + 1) and return @r;
+                }
+            }
+        }
+        Nil;
+    }
+    for 0 .. $N / 2 {
+        if my @f = search [$_], 1 {
+            say ~@f;
+            last;
+        }
+    }
+}
+# output:
+0 4 7 5 2 6 1 3