13 lesson

src/main/java/io/sidorovgreg/otus/App.java

@@ -1,33 +1,11 @@
 package io.sidorovgreg.otus;
 
-import java.lang.reflect.Constructor;
-import java.nio.file.Files;
-import java.nio.file.NoSuchFileException;
-import java.nio.file.Paths;
-import java.util.List;
-import java.util.Objects;
+import java.util.stream.IntStream;
 
 public class App {
-    public static void main(String[] args) throws Exception {
-        Class<?> clazz = Class.forName("io.sidorovgreg.otus.tasks." + args[0]);
-        Constructor<?> ctor = clazz.getConstructor();
-        Task task = (Task) ctor.newInstance();
-        String path = args[1];
-        for (int i = 0; true; i++) {
-            try {
-                List<String> in = Files.readAllLines(Paths.get(String.format("%s/test.%s.in", path, i)));
-                String out = Files.readAllLines(Paths.get(String.format("%s/test.%s.out", path, i))).stream()
-                        .findFirst()
-                        .orElseThrow(() -> new RuntimeException("expected result isn't exist"));
-                String result = task.execute(in);
-                if (Objects.equals(result, out)) {
-                    System.out.printf("[%s] success%n", in);
-                } else {
-                    System.out.printf("[%s] fail: got %s, expected %s %n", in, result, out);
-                }
-            } catch (NoSuchFileException e) {
-                break;
-            }
-        }
+    public static void main(String[] args) {
+        CustomMap<Integer, Double> map = new CustomMap<>();
+        IntStream.range(0, 100).forEach(i -> map.put(i, Math.pow(10, i)));
+        System.out.println(map.get(99));
     }
 }

src/main/java/io/sidorovgreg/otus/CustomMap.java

@@ -0,0 +1,120 @@
+package io.sidorovgreg.otus;
+
+import java.util.ArrayList;
+import java.util.Objects;
+
+public class CustomMap<K, V> {
+    private ArrayList<CustomMapNode<K, V>> bucketArray;
+
+    private int numBuckets;
+
+    private int size;
+
+    public CustomMap() {
+        bucketArray = new ArrayList<>();
+        numBuckets = 10;
+        size = 0;
+
+        // Create empty chains
+        for (int i = 0; i < numBuckets; i++)
+            bucketArray.add(null);
+    }
+
+    public int size() {
+        return size;
+    }
+
+    public boolean isEmpty() {
+        return size() == 0;
+    }
+
+    private int hashCode(K key) {
+        return Objects.hashCode(key);
+    }
+
+    private int getBucketIndex(K key) {
+        int hashCode = hashCode(key);
+        int index = hashCode % numBuckets;
+        index = index < 0 ? index * -1 : index;
+        return index;
+    }
+
+    public V del(K key) {
+        int bucketIndex = getBucketIndex(key);
+        int hashCode = hashCode(key);
+        CustomMapNode<K, V> head = bucketArray.get(bucketIndex);
+
+        CustomMapNode<K, V> prev = null;
+        while (head != null) {
+            if (head.key.equals(key) && hashCode == head.hashCode)
+                break;
+
+            prev = head;
+            head = head.next;
+        }
+
+        if (head == null)
+            return null;
+
+        size--;
+
+        if (prev != null)
+            prev.next = head.next;
+        else
+            bucketArray.set(bucketIndex, head.next);
+
+        return head.value;
+    }
+
+    public V get(K key) {
+        int bucketIndex = getBucketIndex(key);
+        int hashCode = hashCode(key);
+
+        CustomMapNode<K, V> head = bucketArray.get(bucketIndex);
+
+        while (head != null) {
+            if (head.key.equals(key) && head.hashCode == hashCode)
+                return head.value;
+            head = head.next;
+        }
+
+        return null;
+    }
+
+    public void put(K key, V value) {
+        int bucketIndex = getBucketIndex(key);
+        int hashCode = hashCode(key);
+        CustomMapNode<K, V> head = bucketArray.get(bucketIndex);
+
+        while (head != null) {
+            if (head.key.equals(key) && head.hashCode == hashCode) {
+                head.value = value;
+                return;
+            }
+            head = head.next;
+        }
+
+        size++;
+        head = bucketArray.get(bucketIndex);
+        CustomMapNode<K, V> newNode
+                = new CustomMapNode<>(key, value, hashCode);
+        newNode.next = head;
+        bucketArray.set(bucketIndex, newNode);
+
+        if ((1.0 * size) / numBuckets >= 0.7) {
+            ArrayList<CustomMapNode<K, V>> temp = bucketArray;
+            bucketArray = new ArrayList<>();
+            numBuckets = 2 * numBuckets;
+            size = 0;
+            for (int i = 0; i < numBuckets; i++)
+                bucketArray.add(null);
+
+            for (CustomMapNode<K, V> headNode : temp) {
+                while (headNode != null) {
+                    put(headNode.key, headNode.value);
+                    headNode = headNode.next;
+                }
+            }
+        }
+    }
+}

src/main/java/io/sidorovgreg/otus/CustomMapNode.java

@@ -0,0 +1,18 @@
+package io.sidorovgreg.otus;
+
+public class CustomMapNode<K, V> {
+    K key;
+    V value;
+    final int hashCode;
+
+    // Reference to next node
+    CustomMapNode<K, V> next;
+
+    // Constructor
+    public CustomMapNode(K key, V value, int hashCode)
+    {
+        this.key = key;
+        this.value = value;
+        this.hashCode = hashCode;
+    }
+}