Question 4 of leetcode, add two numbers

Original question:

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)Output: 7 -> 0 -> 8

Question Analysis:

Two linked lists are given to indicate two non-negative values. Numbers are stored in reverse order. Each node contains a single number. Calculate the sum of the two linked lists and return the results in the same format.

The solution is to directly add the linked list ..

The Code is as follows:

C ++

class Solution {public:ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {ListNode * ans = NULL, *last = NULL;int up = 0;while (NULL != l1 && NULL != l2) {int tmp = l1->val + l2->val + up;up = tmp / 10;if (NULL == last) {ans = new ListNode(tmp % 10);last = ans;} elselast = pushBack(last, tmp % 10);l1 = l1->next;l2 = l2->next;}while (NULL != l1) {int tmp = l1->val + up;last = pushBack(last, tmp % 10);up = tmp / 10;l1 = l1->next;}while (NULL != l2) {int tmp = l2->val + up;last = pushBack(last, tmp % 10);up = tmp / 10;l2 = l2->next;}if (0 != up) {ListNode * l = new ListNode(up);last->next = l;}return ans;}ListNode * pushBack(ListNode * last, int val) {ListNode * l = new ListNode(val);last->next = l;return l;}};

Python

# class ListNode:#     def __init__(self, x):#         self.val = x#         self.next = None class Solution:    # @return a ListNode    def addTwoNumbers(self, l1, l2):        carry = 0; head = ListNode(0); curr = head;        while l1 and l2:            Sum = l1.val + l2.val + carry            carry = Sum / 10            curr.next = ListNode(Sum % 10)            l1 = l1.next; l2 = l2.next; curr = curr.next        while l1:            Sum = l1.val + carry            carry = Sum / 10            curr.next = ListNode(Sum % 10)            l1 = l1.next; curr = curr.next        while l2:            Sum = l2.val + carry            carry = Sum / 10            curr.next = ListNode(Sum % 10)            l2 = l2.next; curr = curr.next        if carry > 0:            curr.next = ListNode(carry)        return head.next

One piece of water ....