HashSet lesson & examples added

Author: halilozel1903

src/HashSet.kt

@@ -0,0 +1,41 @@
+fun main() {
+
+    /*
+        HashSet is a generic unordered collection of elements and it does not contain duplicate elements.
+
+        It implements the set interface. hashSetOf() is a function which returns a mutable hashSet,
+        which can be both read and written.
+
+        The HashSet class store all the elements using hashing mechanism.
+     */
+
+
+    // declaring a hashSet of chars
+    val chars = hashSetOf('p','a','z','w')
+
+    // println set contains
+    println(chars)
+
+    // You can add elements in a hashset using add() and addAll() functions.
+    chars.add('c')
+
+
+    val newChars = setOf('b','o')
+
+    //making an extra set to add it in chars
+    chars.addAll(newChars)
+
+    println(chars)
+
+    /*
+        HashSet there is a hash value calculated for each object and this hash value determines the array index of the
+        particular object in the container. So the order of inserted elements are naturally not preserved.
+        This allows for accessing desired elements with O(1) complexity but it costs a lot of memory
+
+        For more : https://en.wikipedia.org/wiki/Hash_table
+
+     */
+
+    // removing a from the set
+    chars.remove('a')
+}