From 11983e0f081996b22e64a84aa408d297ef05ece3 Mon Sep 17 00:00:00 2001
From: Manuel Thalmann <m@nuth.ch>
Date: Wed, 16 Nov 2022 21:53:44 +0100
Subject: [PATCH] Implement basic functionality of `MyHashTable`

---
 .../java/ch/nuth/zhaw/exbox/MyHashtable.java  | 63 ++++++++++++++-----
 1 file changed, 48 insertions(+), 15 deletions(-)

diff --git a/app/src/main/java/ch/nuth/zhaw/exbox/MyHashtable.java b/app/src/main/java/ch/nuth/zhaw/exbox/MyHashtable.java
index 4db3d6d..904fab8 100644
--- a/app/src/main/java/ch/nuth/zhaw/exbox/MyHashtable.java
+++ b/app/src/main/java/ch/nuth/zhaw/exbox/MyHashtable.java
@@ -6,37 +6,69 @@ import java.util.Set;
 
 @SuppressWarnings("unchecked")
 public class MyHashtable<K, V> implements Map<K, V> {
+    private int capacity;
+    private int size;
     private K[] keys = (K[]) new Object[10];
     private V[] values = (V[]) new Object[10];
 
+    public MyHashtable(int size) {
+        capacity = size;
+        clear();
+    }
+
+    private boolean hashEquals(Object x, Object y) {
+        if (x == null || y == null) {
+            return x == y;
+        } else {
+            return x.hashCode() == y.hashCode();
+        }
+    }
+
     private int hash(Object k) {
         int h = Math.abs(k.hashCode());
         return h % keys.length;
     }
 
-    public MyHashtable(int size) {
-        // to be done
-    }
-
     // Removes all mappings from this map (optional operation).
     public void clear() {
-        // to be done
-        throw new UnsupportedOperationException();
+        keys = (K[]) new Object[capacity];
+        values = (V[]) new Object[capacity];
     }
 
-    // Associates the specified value with the specified key in this map (optional operation).
+    // Associates the specified value with the specified key in this map (optional
+    // operation).
     public V put(K key, V value) {
-        // to be done
-        throw new UnsupportedOperationException();
+        int hashCode = hash(key);
+        int index = hashCode;
+
+        for (int i = 0; keys[index] != null && !hashEquals(keys[index], key); i++) {
+            index = hash(hashCode + (int) Math.pow(i, 2));
+        }
+
+        if (keys[index] == null) {
+            size++;
+        }
+
+        keys[index] = key;
+        values[index] = value;
+
+        return value;
     }
 
     // Returns the value to which this map maps the specified key.
     public V get(Object key) {
         // to be done
-        throw new UnsupportedOperationException();
+        for (int i = 0; i < keys.length; i++) {
+            if (hashEquals(key, keys[i])) {
+                return values[i];
+            }
+        }
+
+        return null;
     }
 
-    // Removes the mapping for this key from this map if present (optional operation).
+    // Removes the mapping for this key from this map if present (optional
+    // operation).
     public V remove(Object key) {
         // to be done (Aufgabe 3)
         throw new UnsupportedOperationException();
@@ -44,11 +76,11 @@ public class MyHashtable<K, V> implements Map<K, V> {
 
     // Returns the number of key-value mappings in this map.
     public int size() {
-        // to be done
-        throw new UnsupportedOperationException();
+        return size;
     }
 
-    // UnsupportedOperationException ===================================================================
+    // UnsupportedOperationException
+    // ===================================================================
     // Returns a collection view of the values contained in this map.
     public Collection<V> values() {
         throw new UnsupportedOperationException();
@@ -74,7 +106,8 @@ public class MyHashtable<K, V> implements Map<K, V> {
         throw new UnsupportedOperationException();
     }
 
-    // Copies all of the mappings from the specified map to this map (optional operation).
+    // Copies all of the mappings from the specified map to this map (optional
+    // operation).
     public void putAll(Map<? extends K, ? extends V> t) {
         throw new UnsupportedOperationException();
     }