Create AddTwoNumbers.java

Author: Foxeyyy

AddTwoNumbers.java

@@ -0,0 +1,46 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+ 
+ //Space: O(1)
+ //Time: O(max(len(l1), len(l2))
+class Solution {
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+        
+        ListNode dummy = new ListNode(0);
+        
+        ListNode sol = dummy;
+        
+        int carry = 0; 
+        
+        while(l1 != null || l2 != null) {
+            
+            int curr = 0;
+            if (l1 != null) curr += l1.val;
+            if (l2 != null) curr += l2.val;
+            curr += carry;
+                        
+            sol.next = new ListNode(curr % 10);
+            carry = curr / 10;
+
+            sol = sol.next;
+            if (l1 != null) l1 = l1.next;
+            if (l2 != null) l2 = l2.next;
+            
+        }
+        
+        if (carry > 0) {
+            sol.next = new ListNode(carry);
+        }
+        
+        return dummy.next;
+        
+    }
+}