HashMap done

Author: rampatra

src/main/java/com/leetcode/hashtables/MyHashMap.java

@@ -0,0 +1,105 @@
+package com.leetcode.hashtables;
+
+/**
+ * Level: Learning cards
+ * Problem Link: https://leetcode.com/explore/learn/card/hash-table/182/practical-applications/1140/ 
+ * Runtime: https://leetcode.com/submissions/detail/224928756/
+ * 
+ * @author rampatra
+ * @since 2019-04-25
+ */
+public class MyHashMap {
+
+    class Entry {
+        int key;
+        int value;
+        Entry next;
+
+        Entry(int key, int value) {
+            this.key = key;
+            this.value = value;
+        }
+    }
+
+    private final int SIZE = 10000;
+    private final Entry[] entries;
+
+    /**
+     * Initialize your data structure here.
+     */
+    public MyHashMap() {
+        entries = new Entry[SIZE];
+    }
+
+    /**
+     * value will always be non-negative.
+     */
+    public void put(int key, int value) {
+        int bucket = key % SIZE;
+        Entry entry = entries[bucket];
+
+        if (entry == null) {
+            entries[bucket] = new Entry(key, value);
+        } else {
+            while (entry.next != null && entry.key != key) {
+                entry = entry.next;
+            }
+
+            if (entry.key == key) {
+                entry.value = value;
+            } else {
+                entry.next = new Entry(key, value);
+            }
+        }
+    }
+
+    /**
+     * Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
+     */
+    public int get(int key) {
+        int bucket = key % SIZE;
+        Entry entry = entries[bucket];
+        while (entry != null) {
+            if (entry.key == key) {
+                return entry.value;
+            }
+            entry = entry.next;
+        }
+        return -1;
+    }
+
+    /**
+     * Removes the mapping of the specified value key if this map contains a mapping for the key
+     */
+    public void remove(int key) {
+        int bucket = key % SIZE;
+        Entry entry = entries[bucket];
+
+        if (entry != null && entry.key == key) {
+            entries[bucket] = entry.next;
+            return;
+        }
+
+        Entry curr = new Entry(0, 0);
+        curr.next = entry;
+
+        while (curr.next != null && curr.next.key != key) {
+            curr = curr.next;
+        }
+
+        if (curr.next != null) {
+            curr.next = curr.next.next;
+        }
+    }
+
+    public static void main(String[] args) {
+        MyHashMap map = new MyHashMap();
+        map.put(1, 2);
+        System.out.println("1 -> " + map.get(1));
+        map.put(1, 4);
+        System.out.println("1 -> " + map.get(1));
+        map.remove(1);
+        System.out.println("1 -> " + map.get(1));
+        System.out.println("5 -> " + map.get(5));
+    }
+}

src/main/java/com/leetcode/hashtables/MyHashSet.java

@@ -3,6 +3,7 @@
 /**
  * Level: Learning Cards
  * Problem Link: https://leetcode.com/explore/learn/card/hash-table/182/practical-applications/1139/
+ * Runtime: https://leetcode.com/submissions/detail/224872991/
  *
  * @author rampatra
  * @since 2019-04-24
@@ -30,7 +31,7 @@ public MyHashSet() {
 
     public void add(int key) {
         if (contains(key)) return;
-        
+
         Entry newEntry = new Entry(key);
         int bucket = key % SIZE;
 
@@ -41,19 +42,19 @@ public void add(int key) {
     public void remove(int key) {
         int bucket = key % SIZE;
         Entry entry = entries[bucket];
-        
+
         if (entry != null && entry.key == key) {
             entries[bucket] = entry.next;
             return;
         }
-        
+
         Entry curr = new Entry(0);
         curr.next = entry;
-        
+
         while (curr.next != null && curr.next.key != key) {
             curr = curr.next;
         }
-        
+
         if (curr.next != null) {
             curr.next = curr.next.next;
         }