Create 445. Add Two Numbers II

Linked list

Author: Manikant69

Diff for: 445. Add Two Numbers II

@@ -0,0 +1,97 @@
+/**
+ * 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* reverse(ListNode* head)
+    {
+        ListNode* curr = head;
+        ListNode* prev = NULL;
+        ListNode* Next = NULL;
+
+        while(curr != NULL)
+        {
+            Next = curr -> next;
+            curr -> next = prev;
+            prev = curr;
+            curr = Next;
+        }
+
+        return prev;
+    }
+    void insertAtTail(ListNode* &head, ListNode* &tail, int d)
+    {
+        ListNode* temp = new ListNode(d);
+        
+        if(head == NULL)
+        {
+            head = temp;
+            tail = temp;
+        }
+        else
+        {
+            tail -> next = temp;
+            tail = temp;
+        }
+    }
+
+    ListNode* add(ListNode* first, ListNode* second)
+    {
+        if(first == NULL)
+            return second;
+        if(second == NULL)
+            return first;
+        
+        ListNode* ansHead = NULL;
+        ListNode* ansTail = NULL;
+        int carry = 0;
+
+        while(first != NULL || second != NULL || carry != 0)
+        {
+            int val1 = 0, val2 = 0;
+            if(first != NULL)
+                val1 = first -> val;
+            if(second != NULL)
+                val2 = second -> val;
+
+            int sum = val1 + val2 + carry;
+            int digit = sum % 10;
+
+            insertAtTail(ansHead, ansTail, digit);
+
+            carry = sum / 10;
+
+            if(first != NULL)
+                first = first -> next;
+            if(second != NULL)
+                second = second -> next;
+        }
+
+        return ansHead;
+    }
+
+
+    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
+        //reverse the given linked lists
+        l1 = reverse(l1);
+        l2 = reverse(l2);
+
+        //add from left
+        ListNode* ans = add(l1, l2);
+
+
+        //revert the ans
+        ans = reverse(ans);
+
+
+        return ans;
+        
+    }
+};