Shirlies 宁静专注认真的程序媛~

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

1、直接按顺序加就行，保存进位carry

2、到最后还需要考虑进位carry是否为0

 1 /**
2  * Definition for singly-linked list.
3  * struct ListNode {
4  *     int val;
5  *     ListNode *next;
6  *     ListNode(int x) : val(x), next(NULL) {}
7  * };
8  */
9 class Solution {
10 public:
11     ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
12         if(l1 == NULL)
13         {
14             return l2;
15         }
16
17         if(l2 == NULL)
18         {
19             return l1;
20         }
21
22         ListNode *ans = NULL;
23         ListNode *point = NULL;
24         int carry = 0;
25         int sum = 0;
26         while(l1 != NULL && l2 != NULL)
27         {
28             sum = carry + l1->val + l2->val;
29             carry = sum / 10;
30             sum = sum % 10;
31
32             ListNode *value = new ListNode(sum);
33             if(ans == NULL)
34             {
35                 ans = value;
36             }
37
38             if(point != NULL)
39             {
40                 point->next = value;
41             }
42             point = value;
43
44             l1 = l1->next;
45             l2 = l2->next;
46         }
47
48         while(l1 != NULL)
49         {
50             sum = carry + l1->val;
51             carry = sum / 10;
52             sum = sum % 10;
53             ListNode *value = new ListNode(sum);
54             point->next = value;
55             point = value;
56
57             l1 = l1->next;
58         }
59
60         while(l2 != NULL)
61         {
62             sum = carry + l2->val;
63             carry = sum / 10;
64             sum = sum % 10;
65             ListNode *value = new ListNode(sum);
66             point->next = value;
67             point = value;
68
69             l2 = l2->next;
70         }
71
72         if(carry != 0)
73         {
74             ListNode *value = new ListNode(carry);
75             point->next = value;
76             point = value;
77         }
78
79         return ans;
80     }
81 };
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posted on 2016-07-20 20:36  Shirlies  阅读(239)  评论(0编辑  收藏  举报