Data commit

Task/Yellowstone-sequence/D/yellowstone-sequence.d

@@ -0,0 +1,49 @@
+import std.numeric;
+import std.range;
+import std.stdio;
+
+class Yellowstone {
+    private bool[int] sequence_;
+    private int min_ = 1;
+    private int n_ = 0;
+    private int n1_ = 0;
+    private int n2_ = 0;
+
+    public this() {
+        popFront();
+    }
+
+    public bool empty() {
+        return false;
+    }
+
+    public int front() {
+        return n_;
+    }
+
+    public void popFront() {
+        n2_ = n1_;
+        n1_ = n_;
+        if (n_ < 3) {
+            ++n_;
+        } else {
+            for (n_ = min_;
+                !(n_ !in sequence_ && gcd(n1_, n_) == 1 && gcd(n2_, n_) > 1);
+                ++n_) {
+                // empty
+            }
+        }
+        sequence_[n_] = true;
+        while (true) {
+            if (min_ !in sequence_) {
+                break;
+            }
+            sequence_.remove(min_);
+            ++min_;
+        }
+    }
+}
+
+void main() {
+    new Yellowstone().take(30).writeln();
+}