Data commit

Task/Knuths-power-tree/Java/knuths-power-tree.java

@@ -0,0 +1,67 @@
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class PowerTree {
+    private static Map<Integer, Integer> p = new HashMap<>();
+    private static List<List<Integer>> lvl = new ArrayList<>();
+
+    static {
+        p.put(1, 0);
+
+        ArrayList<Integer> temp = new ArrayList<>();
+        temp.add(1);
+        lvl.add(temp);
+    }
+
+    private static List<Integer> path(int n) {
+        if (n == 0) return new ArrayList<>();
+        while (!p.containsKey(n)) {
+            List<Integer> q = new ArrayList<>();
+            for (Integer x : lvl.get(0)) {
+                for (Integer y : path(x)) {
+                    if (p.containsKey(x + y)) break;
+                    p.put(x + y, x);
+                    q.add(x + y);
+                }
+            }
+            lvl.get(0).clear();
+            lvl.get(0).addAll(q);
+        }
+        List<Integer> temp = path(p.get(n));
+        temp.add(n);
+        return temp;
+    }
+
+    private static BigDecimal treePow(double x, int n) {
+        Map<Integer, BigDecimal> r = new HashMap<>();
+        r.put(0, BigDecimal.ONE);
+        r.put(1, BigDecimal.valueOf(x));
+
+        int p = 0;
+        for (Integer i : path(n)) {
+            r.put(i, r.get(i - p).multiply(r.get(p)));
+            p = i;
+        }
+        return r.get(n);
+    }
+
+    private static void showPow(double x, int n, boolean isIntegral) {
+        System.out.printf("%d: %s\n", n, path(n));
+        String f = isIntegral ? "%.0f" : "%f";
+        System.out.printf(f, x);
+        System.out.printf(" ^ %d = ", n);
+        System.out.printf(f, treePow(x, n));
+        System.out.println("\n");
+    }
+
+    public static void main(String[] args) {
+        for (int n = 0; n <= 17; ++n) {
+            showPow(2.0, n, true);
+        }
+        showPow(1.1, 81, false);
+        showPow(3.0, 191, true);
+    }
+}