Im bored

Author: ChSatyaSavith

21. Merge Two Sorted Lists.cpp

@@ -0,0 +1,98 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
+        ListNode* head = NULL;
+        ListNode* prev = NULL;
+        if(list1==NULL && list2==NULL)
+        {
+            return head;
+        }
+        while(list1!=NULL && list2!=NULL)
+        {
+            ListNode* newnode = new ListNode();
+
+            if(list1->val < list2->val)
+            {
+                newnode->val = list1->val;
+                newnode->next = NULL;
+                if(head==NULL)
+                {
+                    head = newnode;
+                    prev = newnode;
+                }
+                else
+                {
+                    prev->next = newnode;
+                    prev = newnode;
+                }
+                list1 = list1->next;
+            }
+            else
+            {
+                newnode->val = list2->val;
+                newnode->next = NULL;
+                if(head==NULL)
+                {
+                    head = newnode;
+                    prev = newnode;
+                }
+                else
+                {
+                    prev->next = newnode;
+                    prev = newnode;
+                }
+                list2 = list2->next;
+            }
+        }
+
+        if(list1==NULL && list2!=NULL)
+        {
+            if(prev!=NULL)
+            {
+                while(list2!=NULL)
+                {
+                    ListNode* newnode = new ListNode();
+                    newnode->val = list2->val;
+                    newnode->next = NULL;
+                    prev->next = newnode;
+                    prev = newnode;
+                    list2 = list2->next;
+                }
+            }
+            else
+            {
+                head = list2;
+            }
+        }
+        else if(list1!=NULL && list2==NULL)
+        {
+            if(prev!=NULL)
+            {
+                while(list1!=NULL)
+                {
+                    ListNode* newnode = new ListNode();
+                    newnode->val = list1->val;
+                    newnode->next = NULL;
+                    prev->next = newnode;
+                    prev = newnode;
+                    list1 = list1->next;
+                }
+            }
+            else
+            {
+                head = list1;
+            }
+        }
+        return head;
+    }
+};