Update 0002-Add-Two-Numbers.md

添加Java、Python代码实现

0002-Add-Two-Numbers/Article/0002-Add-Two-Numbers.md

@@ -32,7 +32,8 @@
 
 ### 代码实现
 
-```
+#### C++
+```c++
 /// 时间复杂度: O(n)
 /// 空间复杂度: O(n)
 /**
@@ -70,7 +71,68 @@ public:
 };
 
 ```
+#### Java
+```java
+class Solution {
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+        ListNode dummyHead = new ListNode(0);
+        ListNode cur = dummyHead;
+        int carry = 0;
 
+        while(l1 != null || l2 != null)
+        {
+            int sum = carry;
+            if(l1 != null)
+            {
+                sum += l1.val;
+                l1 = l1.next;
+            }
+            if(l2 != null)
+            {
+                sum += l2.val;
+                l2 = l2.next;
+            }
+            // 创建新节点
+            carry = sum / 10;
+            cur.next = new ListNode(sum % 10);
+            cur = cur.next;
+    
+        }
+        if (carry > 0) {
+            cur.next = new ListNode(carry);
+        }
+        return dummyHead.next;
+    }
+}
+```
+#### Python
+```python
+class Solution(object):
+    def addTwoNumbers(self, l1, l2):
+        res=ListNode(0)
+        head=res
+        carry=0
+        while l1 or l2 or carry!=0:
+            sum=carry
+            if l1:
+                sum+=l1.val
+                l1=l1.next
+            if l2:
+                sum+=l2.val
+                l2=l2.next
+            # set value
+            if sum<=9:
+                res.val=sum
+                carry=0
+            else:
+                res.val=sum%10
+                carry=sum//10
+            # creat new node
+            if l1 or l2 or carry!=0:
+                res.next=ListNode(0)
+                res=res.next
+        return head
+```
 
 
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