algorithm001
diff --git a/Week_01/id_56/LeetCode_21_056.cpp b/Week_01/id_56/LeetCode_21_056.cpp
@@ -0,0 +1,22 @@
+public class Solution {
+     public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
+         if(l1 == null && l2 == null)
+             return null;
+         if(l1 == null)
+             return l2;
+         if(l2 == null)
+             return l1;
+         ListNode head = null;
+         if(l1.val > l2.val)
+         {
+              head = l2;
+              head.next = mergeTwoLists(l1, l2.next);
+         }
+         else
+         {
+              head = l1;
+              head.next = mergeTwoLists(l1.next, l2);
+         }
+         return head;
+     }
+ }
diff --git a/Week_01/id_56/LeetCode_83_056.cpp b/Week_01/id_56/LeetCode_83_056.cpp
@@ -0,0 +1,17 @@
+class Solution {
+public:
+    ListNode* deleteDuplicates(ListNode* head) {
+        if ((head == nullptr) || (head->next == nullptr))  return head;
+        ListNode* node = head;
+        ListNode* nextNode = node->next;
+        while (nextNode != nullptr) {
+            if (nextNode->val == node->val) {
+                node->next = nextNode->next;
+                nextNode->next = nullptr;
+            } else node = nextNode;
+            nextNode = node->next;
+        }
+
+        return head;
+    }
+};