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JanaSabuj · JanaSabuj · commit d055b48535a2 · 2022-08-14T21:59:31.000+05:30
diff --git a/21-merge-two-sorted-lists/21-merge-two-sorted-lists.cpp b/21-merge-two-sorted-lists/21-merge-two-sorted-lists.cpp
@@ -0,0 +1,41 @@
+/**
+ * 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* dummy = new ListNode(0);
+        ListNode* curr = dummy;
+
+        // curr     l11 l12  ....
+        //  curr -> l11
+        //    ^       ^
+        while (list1 != NULL and list2 != NULL) {
+            if (list1->val <= list2->val) {
+                curr->next = list1;
+                list1 = list1->next;
+            } else {
+                curr->next = list2;
+                list2 = list2->next;
+            }
+            curr = curr->next;
+        }
+
+        // curr
+        //       n n n
+        if (list1 != NULL)
+            curr->next = list1;
+
+        if (list2 != NULL)
+            curr->next = list2;
+
+        return dummy->next;
+    }
+};
