Initial data commit

Task/List-rooted-trees/Java/list-rooted-trees.java

@@ -0,0 +1,91 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class ListRootedTrees {
+    private static final List<Long> TREE_LIST = new ArrayList<>();
+
+    private static final List<Integer> OFFSET = new ArrayList<>();
+
+    static {
+        for (int i = 0; i < 32; i++) {
+            if (i == 1) {
+                OFFSET.add(1);
+            } else {
+                OFFSET.add(0);
+            }
+        }
+    }
+
+    private static void append(long t) {
+        TREE_LIST.add(1 | (t << 1));
+    }
+
+    private static void show(long t, int l) {
+        while (l-- > 0) {
+            if (t % 2 == 1) {
+                System.out.print('(');
+            } else {
+                System.out.print(')');
+            }
+            t = t >> 1;
+        }
+    }
+
+    private static void listTrees(int n) {
+        for (int i = OFFSET.get(n); i < OFFSET.get(n + 1); i++) {
+            show(TREE_LIST.get(i), n * 2);
+            System.out.println();
+        }
+    }
+
+    private static void assemble(int n, long t, int sl, int pos, int rem) {
+        if (rem == 0) {
+            append(t);
+            return;
+        }
+
+        var pp = pos;
+        var ss = sl;
+
+        if (sl > rem) {
+            ss = rem;
+            pp = OFFSET.get(ss);
+        } else if (pp >= OFFSET.get(ss + 1)) {
+            ss--;
+            if (ss == 0) {
+                return;
+            }
+            pp = OFFSET.get(ss);
+        }
+
+        assemble(n, t << (2 * ss) | TREE_LIST.get(pp), ss, pp, rem - ss);
+        assemble(n, t, ss, pp + 1, rem);
+    }
+
+    private static void makeTrees(int n) {
+        if (OFFSET.get(n + 1) != 0) {
+            return;
+        }
+        if (n > 0) {
+            makeTrees(n - 1);
+        }
+        assemble(n, 0, n - 1, OFFSET.get(n - 1), n - 1);
+        OFFSET.set(n + 1, TREE_LIST.size());
+    }
+
+    private static void test(int n) {
+        if (n < 1 || n > 12) {
+            throw new IllegalArgumentException("Argument must be between 1 and 12");
+        }
+
+        append(0);
+
+        makeTrees(n);
+        System.out.printf("Number of %d-trees: %d\n", n, OFFSET.get(n + 1) - OFFSET.get(n));
+        listTrees(n);
+    }
+
+    public static void main(String[] args) {
+        test(5);
+    }
+}