Деревья

vol6/src/main/java/ru/mifi/practice/vol6/tree/Center.java

@@ -0,0 +1,71 @@
+package ru.mifi.practice.vol6.tree;
+
+import ru.mifi.practice.vol6.tree.visitors.Count;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Function;
+
+/**
+ * Почему реализация не правильная?
+ * @param <T> тип значения в вершине дерева
+ */
+public final class Center<T> {
+    public List<Node<T>> center(Tree<T> tree, Function<? super T, ? extends T> copyFunction) {
+        tree = tree.copy(copyFunction);
+        List<Node<T>> result = new ArrayList<>();
+        Set<Node<T>> leafs = new HashSet<>();
+        VisitorStrategy.PreOrder<T> strategy = new VisitorStrategy.PreOrder<>();
+        Visitor<T> search = new Visitor<>() {
+            @Override
+            public void enterNode(Node<T> node) {
+                if (node.left() == null && node.right() == null) {
+                    leafs.add(node);
+                }
+            }
+
+            @Override
+            public void exitNode(Node<T> node) {
+                //None
+            }
+
+            @Override
+            public void empty() {
+                //None
+            }
+        };
+        Count<T> count = new Count<>();
+        while (true) {
+            count.clear();
+            tree.visit(count, strategy);
+            if (count.count() <= 2) {
+                break;
+            }
+            leafs.clear();
+            tree.visit(search, strategy);
+            for (Node<T> leaf : leafs) {
+                tree.delete(leaf.value());
+            }
+        }
+        tree.visit(new Visitor<T>() {
+
+            @Override
+            public void enterNode(Node<T> node) {
+                result.add(node);
+            }
+
+            @Override
+            public void exitNode(Node<T> node) {
+                //None
+            }
+
+            @Override
+            public void empty() {
+                //None
+            }
+        }, strategy);
+        return result;
+    }
+}

vol6/src/main/java/ru/mifi/practice/vol6/tree/Diameter.java

@@ -21,7 +21,7 @@ public List<Node<T>> path(Tree<T> tree) {
         }
         if (maxNode != null) {
             VisitorStrategy.AlreadyVisited<T> alreadyVisited = new VisitorStrategy.AlreadyVisited<>(strategy);
-            Node<T> start = maxNode;
+            final Node<T> start = maxNode;
             Node<T> it = maxNode;
             int distance = 0;
             vDistance.clear();

vol6/src/main/java/ru/mifi/practice/vol6/tree/Main.java

@@ -47,6 +47,9 @@ public static void main(String[] args) throws IOException {
         System.out.print("EULER: ");
         tree.visit(euler, new VisitorStrategy.PreOrder<>());
         System.out.println(euler);
-        System.out.println(tree);
+        Center<Integer> center = new Center<>();
+        List<Node<Integer>> centered = center.center(tree, integer -> integer);
+        System.out.print("CENTR: ");
+        System.out.println(centered);
     }
 }

vol6/src/main/java/ru/mifi/practice/vol6/tree/Node.java

@@ -79,7 +79,7 @@ public List<Node<T>> path(T element) {
             Node<T> it = search(element);
             while (it != null) {
                 path.push(it);
-                if (it == this) {
+                if (it.equals(this)) {
                     break;
                 }
                 it = it.parent();
@@ -100,7 +100,8 @@ public Node<T> left() {
         @Override
         public Node<T> left(T value) {
             if (value == null) {
-                return left;
+                left = null;
+                return null;
             }
             return left = new Default<>(this, value);
         }
@@ -113,7 +114,8 @@ public Node<T> right() {
         @Override
         public Node<T> right(T value) {
             if (value == null) {
-                return right;
+                right = null;
+                return null;
             }
             return right = new Default<>(this, value);
         }

vol6/src/main/java/ru/mifi/practice/vol6/tree/Tree.java

@@ -14,6 +14,10 @@ public interface Tree<T> extends Visitor.Visit<T> {
     @Override
     void visit(Visitor<T> visitor, VisitorStrategy<T> strategy);
 
+    void delete(T value);
+
+    Tree<T> copy(Function<? super T, ? extends T> copyFunction);
+
     interface Loader<T> {
         Tree<T> parse(InputStream stream, Function<String, T> value, Comparator<T> comparator) throws IOException;
     }
@@ -75,5 +79,51 @@ public Node<T> find(T element) {
             }
             return root.search(element);
         }
+
+        @SuppressWarnings("PMD.EmptyControlStatement")
+        @Override
+        public void delete(T value) {
+            Node<T> node = find(value);
+            if (node == null) {
+                //None
+            } else if (node.parent() != null) {
+                var parent = node.parent();
+                if (parent.left() != null && parent.left().value().equals(value)) {
+                    parent.left(null);
+                } else if (parent.right() != null && parent.right().value().equals(value)) {
+                    parent.right(null);
+                }
+            }
+        }
+
+        @Override
+        public Tree<T> copy(Function<? super T, ? extends T> copyFunction) {
+            Standard<T> tree = new Standard<>(comparator);
+            this.visit(new Visitor<T>() {
+                @Override
+                public void enterNode(Node<T> node) {
+                    Node<T> find = tree.find(node.value());
+                    T left = node.left() == null ? null : copyFunction.apply(node.left().value());
+                    T right = node.right() == null ? null : copyFunction.apply(node.right().value());
+                    if (find == null) {
+                        tree.add(node.value(), left, right);
+                    } else {
+                        find.left(left);
+                        find.right(right);
+                    }
+                }
+
+                @Override
+                public void exitNode(Node<T> node) {
+                    //None
+                }
+
+                @Override
+                public void empty() {
+                    //None
+                }
+            }, new VisitorStrategy.PreOrder<>());
+            return tree;
+        }
     }
 }

vol6/src/main/java/ru/mifi/practice/vol6/tree/Visitor.java

@@ -2,6 +2,7 @@
 
 public interface Visitor<T> {
     void enterNode(Node<T> node);
+
     void exitNode(Node<T> node);
 
     void empty();
@@ -20,7 +21,7 @@ public void enterNode(Node<T> node) {
 
         @Override
         public void exitNode(Node<T> node) {
-
+            //None
         }
 
         @Override

vol6/src/main/java/ru/mifi/practice/vol6/tree/VisitorStrategy.java

@@ -22,8 +22,8 @@ public void visit(Node<T> node, Visitor<T> visitor, VisitorStrategy<T> strategy)
             }
             visited.add(node);
             visitor.enterNode(node);
-            strategy.visit(node.left(), visitor, strategy);
-            strategy.visit(node.right(), visitor, strategy);
+            this.strategy.visit(node.left(), visitor, strategy);
+            this.strategy.visit(node.right(), visitor, strategy);
             visitor.exitNode(node);
         }
     }

vol6/src/main/java/ru/mifi/practice/vol6/tree/visitors/Count.java

@@ -0,0 +1,33 @@
+package ru.mifi.practice.vol6.tree.visitors;
+
+import ru.mifi.practice.vol6.tree.Node;
+import ru.mifi.practice.vol6.tree.Visitor;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public final class Count<T> implements Visitor<T> {
+    private final AtomicInteger count = new AtomicInteger(0);
+
+    public void clear() {
+        count.set(0);
+    }
+
+    public int count() {
+        return count.get();
+    }
+
+    @Override
+    public void enterNode(Node<T> node) {
+        count.incrementAndGet();
+    }
+
+    @Override
+    public void exitNode(Node<T> node) {
+        //None
+    }
+
+    @Override
+    public void empty() {
+        //None
+    }
+}

vol6/src/main/java/ru/mifi/practice/vol6/tree/visitors/Distance.java

@@ -37,6 +37,6 @@ public void exitNode(Node<T> node) {
 
     @Override
     public void empty() {
-
+        //None
     }
 }

vol6/src/main/java/ru/mifi/practice/vol6/tree/visitors/EulerPath.java

@@ -35,7 +35,7 @@ public List<Node<T>> path() {
 
     @Override
     public void empty() {
-
+        //None
     }
 
     @Override

vol6/src/main/java/ru/mifi/practice/vol6/tree/visitors/OnSubTree.java

@@ -65,7 +65,7 @@ public List<Node<T>> times() {
 
     @Override
     public void empty() {
-
+        //None
     }
 
     @Override

vol6/src/main/java/ru/mifi/practice/vol6/tree/visitors/Sequencer.java

@@ -33,6 +33,6 @@ public void exitNode(Node<T> node) {
 
     @Override
     public void empty() {
-
+        //None
     }
 }