From f941aa74a0a19cf027d441b2ce59cd264f51ddee Mon Sep 17 00:00:00 2001
From: Chethana Wickramaarachchi <71955126+Dhavaji@users.noreply.github.com>
Date: Sun, 10 Oct 2021 19:14:24 +0530
Subject: [PATCH 1/2] Create stack.md

---
 stack.md | 122 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 stack.md

diff --git a/stack.md b/stack.md
new file mode 100644
index 0000000..23a4689
--- /dev/null
+++ b/stack.md
@@ -0,0 +1,122 @@
+import static java.lang.System.exit;
+ 
+
+class StackUsingLinkedlist {
+ 
+    
+    private class Node {
+ 
+        int data; 
+        Node link;
+    }
+   
+    Node top;
+    
+    StackUsingLinkedlist()
+    {
+        this.top = null;
+    }
+ 
+    
+    public void push(int x) 
+    {
+        
+        Node temp = new Node();
+ 
+        
+        if (temp == null) {
+            System.out.print("\nHeap Overflow");
+            return;
+        }
+ 
+       
+        temp.data = x;
+ 
+        
+        temp.link = top;
+ 
+        
+        top = temp;
+    }
+ 
+    
+    public boolean isEmpty()
+    {
+        return top == null;
+    }
+ 
+    
+    public int peek()
+    {
+        
+        if (!isEmpty()) {
+            return top.data;
+        }
+        else {
+            System.out.println("Stack is empty");
+            return -1;
+        }
+    }
+ 
+    
+    public void pop() 
+    {
+        
+        if (top == null) {
+            System.out.print("\nStack Underflow");
+            return;
+        }
+ 
+        
+        top = (top).link;
+    }
+ 
+    public void display()
+    {
+        
+        if (top == null) {
+            System.out.printf("\nStack Underflow");
+            exit(1);
+        }
+        else {
+            Node temp = top;
+            while (temp != null) {
+ 
+                
+                System.out.printf("%d->", temp.data);
+ 
+                
+                temp = temp.link;
+            }
+        }
+    }
+}
+// main class
+public class GFG {
+    public static void main(String[] args)
+    {
+        
+        StackUsingLinkedlist obj = new StackUsingLinkedlist();
+        // insert Stack value
+        obj.push(20);
+        obj.push(40);
+        obj.push(60);
+        obj.push(80);
+ 
+        
+        obj.display();
+ 
+        
+        System.out.printf("\nTop element is %d\n", obj.peek());
+ 
+        
+        obj.pop();
+        obj.pop();
+ 
+        
+        obj.display();
+ 
+        
+        System.out.printf("\nTop element is %d\n", obj.peek());
+    }
+}

From a7b185c23691c41290bc6fe658b5f534f7429d9c Mon Sep 17 00:00:00 2001
From: Chethana Wickramaarachchi <71955126+Dhavaji@users.noreply.github.com>
Date: Sat, 22 Oct 2022 11:35:43 +0530
Subject: [PATCH 2/2] Hash table added

---
 Python/HashTable.py | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Python/HashTable.py

diff --git a/Python/HashTable.py b/Python/HashTable.py
new file mode 100644
index 0000000..52bb502
--- /dev/null
+++ b/Python/HashTable.py
@@ -0,0 +1,31 @@
+import pprint
+class Hashtable:
+    def __init__(self, elements):
+        self.bucket_size = len(elements)
+        self.buckets = [[] for i in range(self.bucket_size)]
+        self._assign_buckets(elements)
+    def _assign_buckets(self, elements):
+        for key, value in elements: #calculates the hash of each key
+            hashed_value = hash(key)
+            index = hashed_value % self.bucket_size # positions the element in the bucket using hash
+            self.buckets[index].append((key, value)) #adds a tuple in the bucket
+    def get_value(self, input_key):
+        hashed_value = hash(input_key)
+        index = hashed_value % self.bucket_size
+        bucket = self.buckets[index]
+        for key, value in bucket:
+            if key == input_key:
+                return(value)
+        return None
+    def __str__(self):
+        return pprint.pformat(self.buckets) # pformat returns a printable representation of the object
+if __name__ == "__main__":
+     capitals = [
+        ('France', 'Paris'),
+        ('United States', 'Washington D.C.'),
+        ('Italy', 'Rome'),
+        ('Canada', 'Ottawa')
+    ]
+hashtable = Hashtable(capitals)
+print(hashtable)
+print(f"The capital of Italy is {hashtable.get_value('Italy')}")
\ No newline at end of file