feat: 2025-10-24打卡

2.add-two-numbers.java

@@ -0,0 +1,56 @@
+/*
+ * @lc app=leetcode id=2 lang=java
+ *
+ * [2] Add Two Numbers
+ */
+
+// @lc code=start
+/**
+ * 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; }
+ * }
+ */
+class Solution {
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+        boolean propagated = false;
+        ListNode r = null, cur = null;
+        while(l1!=null ||l2!=null) {
+            int v1 = l1!=null?l1.val:0;
+            int v2 = l2!=null?l2.val:0;
+            int v = v1 + v2 + (propagated?1:0);
+            propagated = v/10!=0;
+            v = v %10;
+            // add node to result
+            ListNode t = new ListNode(v);
+            t.next = null;
+            if(r == null) {
+                r = t;
+                cur = t;
+            } else {
+                cur.next = t;
+                cur = cur.next;
+            }
+
+            if(l1!=null) {
+                l1 = l1.next;
+            }
+            if(l2!=null) {
+                l2 = l2.next;
+            }
+        }
+        if(propagated) {
+            ListNode t = new ListNode(1);
+            t.next = null;
+            cur.next = t;
+            cur = cur.next;
+        }
+        return r;
+    }
+}
+// @lc code=end
+