Add Data Structure "DoublyLL -- Pairs with Sum"

Author: Mohammedvaraliya

Linked List/Doubly Linked List/06_doublyLL_pairs_with_sum.py

@@ -0,0 +1,78 @@
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+        self.prev = None
+
+
+class DoublyLinkedList:
+    def __init__(self):
+        self.head = None
+
+    def append(self, data):
+        new_node = Node(data)
+
+        if self.head is None:
+            new_node.prev = None
+            self.head = new_node
+        else:
+            cur = self.head
+            while cur.next:
+                cur = cur.next
+            cur.next = new_node
+            new_node.prev = cur
+            new_node.next = None
+
+    def prepend(self, data):
+        new_node = Node(data)
+
+        if self.head is None:
+            new_node.prev = None
+            self.head = new_node
+        else:
+            self.head.prev = new_node
+            new_node.next = self.head
+            self.head = new_node
+            new_node.prev = None
+
+    def print_list(self):
+        cur = self.head
+        while cur:
+            print(cur.data)
+            cur = cur.next
+
+    def pairs_with_sum(self, sum_val):
+        pairs = list()
+        p = self.head
+        q = None
+        while p:
+            q = p.next
+            while q:
+                if p.data + q.data == sum_val:
+                    pairs.append("(" + str(p.data) + ", " + str(q.data) + ")")
+                q = q.next
+            p = p.next
+
+        return pairs
+
+
+
+
+
+dllist = DoublyLinkedList()
+dllist.append(1)
+dllist.append(2)
+dllist.append(3)
+dllist.append(4)
+dllist.append(5)
+
+
+dllist.print_list()
+print("\n")
+
+X = dllist.pairs_with_sum(6)
+Y = dllist.pairs_with_sum(0)
+Z = dllist.pairs_with_sum(5)
+print(X)
+print(Y)
+print(Z)

Linked List/Doubly Linked List/Data Structures.md

@@ -4,4 +4,5 @@
 02. Doubly Linked Lists -- Add Node Before/After
 03. Doubly Linked Lists -- Delete Node
 04. Doubly Linked Lists -- Reverse
-05. Doubly Linked Lists -- Remove Duplicates
+05. Doubly Linked Lists -- Remove Duplicates
+06. Doubly Linked Lists -- Pairs with Sum

README.md

@@ -25,6 +25,8 @@
 24. Doubly Linked Lists -- Delete Node
 25. Doubly Linked Lists -- Reverse
 26. Doubly Linked Lists -- Remove Duplicates
+27. Doubly Linked Lists -- Pairs with Sum
+