+add + remove + contains

.gitignore

@@ -0,0 +1,3 @@
+.idea
+target
+*.iml

src/main/java/ua/javarush/map/SimplifiedMap.java

@@ -0,0 +1,8 @@
+package ua.javarush.map;
+
+public interface SimplifiedMap<K,V> {
+    boolean add(K key, V value);
+    boolean remove(K key);
+    boolean contains(K key);
+    int size();
+}

src/main/java/ua/javarush/map/SimplifiedTreeMap.java

@@ -1,5 +1,172 @@
 package ua.javarush.map;
 
-public class SimplifiedTreeMap<K, V> {
+import java.util.Comparator;
 
+public class SimplifiedTreeMap<K extends Comparable<K>, V> implements SimplifiedMap<K, V> {
+    private final Comparator<? super K> comparator;
+    private Entry<K, V> root;
+    private int size;
+
+    public SimplifiedTreeMap() {
+        comparator = null;
+    }
+
+    public SimplifiedTreeMap(Comparator<? super K> comparator) {
+        this.comparator = comparator;
+    }
+
+    @Override
+    public boolean add(K key, V value) {
+        if (size == 0) {
+            root = new Entry<>(key, value, null);
+            size++;
+            return true;
+        }
+
+        Entry<K, V> temp = root;
+        Entry<K, V> parent;
+        int diff;
+
+        do {
+            parent = temp;
+            diff = compare(key, temp.key);
+            if (diff < 0) {
+                temp = temp.left;
+            } else if (diff > 0) {
+                temp = temp.right;
+            } else {
+                temp.value = value;
+                return false;
+            }
+        } while (temp != null);
+
+        Entry<K, V> newEntry = new Entry<>(key, value, parent);
+
+        if (diff > 0) {
+            parent.right = newEntry;
+        } else {
+            parent.left = newEntry;
+        }
+
+        size++;
+        return true;
+    }
+
+    public Entry<K, V> getEntry(K key) {
+        Entry<K, V> temp = root;
+
+        do {
+            int diff = compare(key, temp.key);
+            if (diff < 0) {
+                temp = temp.left;
+            } else if (diff > 0) {
+                temp = temp.right;
+            } else {
+                return temp;
+            }
+        } while (temp != null);
+        return null;
+    }
+
+    @Override
+    public boolean remove(K key) {
+        Entry<K, V> forRemove = getEntry(key);
+        if (forRemove == null) {
+            return false;
+        }
+
+        size--;
+
+        if (size == 1) {
+            if (root.key == key) {
+                root = null;
+            }
+            return true;
+        }
+
+        if (forRemove.left == null && forRemove.right == null) {
+            return removeLeaf(forRemove);
+        }
+
+        if (forRemove.right != null && forRemove.left == null) {
+            if (compare(forRemove.parent.key, forRemove.key) > 0) {
+                forRemove.parent.left = forRemove.right;
+            } else {
+                forRemove.parent.right = forRemove.right;
+            }
+            return true;
+        } else if (forRemove.right == null && forRemove.left != null) {
+            if (compare(forRemove.parent.key, forRemove.key) > 0) {
+                forRemove.parent.left = forRemove.left;
+            } else {
+                forRemove.parent.right = forRemove.left;
+            }
+            return true;
+        }
+
+        removeWithTwoChildren(forRemove);
+        return true;
+    }
+
+    private void removeWithTwoChildren(Entry<K, V> forRemove) {
+        Entry<K, V> lowestLeftChild;
+        Entry<K, V> temp = forRemove.right;
+
+        do {
+            lowestLeftChild = temp;
+            temp = temp.left;
+        } while (temp != null);
+
+        lowestLeftChild.right = forRemove.right;
+        lowestLeftChild.left = forRemove.left;
+
+        if (compare((forRemove.parent).key, forRemove.key) > 0) {
+            (forRemove.parent).left = lowestLeftChild;
+        } else {
+            (forRemove.parent).right = lowestLeftChild;
+        }
+    }
+
+    private boolean removeLeaf(Entry<K, V> forRemove) {
+        if (compare(forRemove.parent.key, forRemove.key) > 0) {
+            forRemove.parent.left = null;
+        } else {
+            forRemove.parent.right = null;
+        }
+        return true;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    @Override
+    public boolean contains(K key) {
+        return getEntry(key) != null;
+    }
+
+    private int compare(K k1, K k2) {
+        return comparator == null ? (k1).compareTo(k2)
+                : comparator.compare(k1, k2);
+    }
+
+    private class Entry<K, V> {
+        private final K key;
+        private V value;
+        private Entry<K, V> left;
+        private Entry<K, V> right;
+        private Entry<K, V> parent;
+
+        private Entry(K key, V value, Entry<K, V> parent) {
+            this.key = key;
+            this.value = value;
+            this.parent = parent;
+        }
+
+        @Override
+        public String toString() {
+            return "key = " + key + ", value = " + value;
+        }
+    }
 }