Merge branch 'HEAD' of https://github.com/soumyadip007/Data-Structure-and-Algorithm-Using-Python.git

Author: soumyadip007

README.md

@@ -1 +1,63 @@
-# Data-Strcture-Algorithm-using-Python
+# Data-Strcture-Algorithm-using-Python
+
+
+Topics:
+ * Queues
+ * Stacks
+ * Doubly Linked Lists
+ * Singly Linked Lists
+ * Binary Search Trees
+ * Tree Traversal
+ * Sortings
+ * Searchings
+ * Dynamic Programming
+ * Heap
+ * Graph
+ 
+### Queues
+ * Should have the methods: `enqueue`, `dequeue`, and `len`.
+   * `enqueue` should add an item to the back of the queue.
+   * `dequeue` should remove and return an item from the front of the queue.
+   * `len` returns the number of items in the queue.
+   
+
+![Image of Queue](https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Data_Queue.svg/600px-Data_Queue.svg.png)
+
+### Doubly Linked Lists
+ * The `ListNode` class, which represents a single node in the doubly-linked list, has already been implemented for you. Inspect this code and try to understand what it is doing to the best of your ability.
+ * The `DoublyLinkedList` class itself should have the methods: `add_to_head`, `add_to_tail`, `remove_from_head`, `remove_from_tail`, `move_to_front`, `move_to_end`, `delete`, and `get_max`.
+   * `add_to_head` replaces the head of the list with a new value that is passed in.
+   * `add_to_tail` replaces the tail of the list with a new value that is passed in.
+   * `remove_from_head` removes the head node and returns the value stored in it.
+   * `remove_from_tail` removes the tail node and returns the value stored in it.
+   * `move_to_front` takes a reference to a node in the list and moves it to the front of the list, shifting all other list nodes down. 
+   * `move_to_end` takes a reference to a node in the list and moves it to the end of the list, shifting all other list nodes up. 
+   * `delete` takes a reference to a node in the list and removes it from the list. The deleted node's `previous` and `next` pointers should point to each afterwards.
+   * `get_max` returns the maximum value in the list. 
+ * The `head` property is a reference to the first node and the `tail` property is a reference to the last node.
+ 
+![Image of Doubly Linked List](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Doubly-linked-list.svg/610px-Doubly-linked-list.svg.png)
+
+### Binary Search Trees
+* Should have the methods `insert`, `contains`, `get_max`.
+  * `insert` adds the input value to the binary search tree, adhering to the rules of the ordering of elements in a binary search tree.
+  * `contains` searches the binary search tree for the input value, returning a boolean indicating whether the value exists in the tree or not.
+  * `get_max` returns the maximum value in the binary search tree.
+  * `for_each` performs a traversal of _every_ node in the tree, executing the passed-in callback function on each tree node value. There is a myriad of ways to perform tree traversal; in this case any of them should work. 
+
+![Image of Binary Search Tree](https://upload.wikimedia.org/wikipedia/commons/thumb/d/da/Binary_search_tree.svg/300px-Binary_search_tree.svg.png)
+
+### Heaps
+* Should have the methods `insert`, `delete`, `get_max`, `_bubble_up`, and `_sift_down`.
+  * `insert` adds the input value into the heap; this method should ensure that the inserted value is in the correct spot in the heap
+  * `delete` removes and returns the 'topmost' value from the heap; this method needs to ensure that the heap property is maintained after the topmost element has been removed. 
+  * `get_max` returns the maximum value in the heap _in constant time_.
+  * `get_size` returns the number of elements stored in the heap.
+  * `_bubble_up` moves the element at the specified index "up" the heap by swapping it with its parent if the parent's value is less than the value at the specified index.
+  * `_sift_down` grabs the indices of this element's children and determines which child has a larger value. If the larger child's value is larger than the parent's value, the child element is swapped with the parent.
+
+![Image of a Heap in Tree form](https://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Max-Heap.svg/501px-Max-Heap.svg.png)
+
+![Image of a Heap in Array form](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Heap-as-array.svg/603px-Heap-as-array.svg.png)
+
+