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
将两个链表上的数相加就可以,大于10进一位,注意下相加时候的细节就可以了,我这里
吧prev节点记录下来,这样最后多生成节点的时候便于将最后一个多余的节点删除:
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 ListNode * curr = new ListNode(0); 13 ListNode * root = curr; 14 ListNode * prev = curr; 15 int currVal = 0; 16 while(l1 != NULL && l2 != NULL){ 17 currVal = l1->val + l2->val; 18 curr->val += currVal; 19 curr->next = new ListNode(curr->val/10); 20 curr->val%=10; 21 prev = curr; 22 curr = curr->next; 23 l1 = l1->next; 24 l2 = l2->next; 25 } 26 while(l1 != NULL){ 27 curr->val += l1->val; 28 curr->next = new ListNode(curr->val/10); 29 curr->val %= 10; 30 prev = curr; 31 curr = curr->next; 32 l1 = l1->next; 33 } 34 while(l2 != NULL){ 35 curr->val += l2->val; 36 curr->next = new ListNode(curr->val/10); 37 curr->val %= 10; 38 prev = curr; 39 curr = curr->next; 40 l2 = l2->next; 41 } 42 if(curr->val == 0){ 43 prev->next = NULL; 44 delete curr; 45 } 46 return root; 47 } 48 };
感觉写的有点麻烦,应该有很多的重复代码可以改正,但是我暂时找不出来了,先这样吧。
更新下,以前脑子抽了写出了那样的代码。 其实三个while循环都可以放到一个while中, 下面用java在写一起,方法还是类似的:
1 /** 2 * Definition for singly-linked list. 3 * public class ListNode { 4 * int val; 5 * ListNode next; 6 * ListNode(int x) { val = x; } 7 * } 8 */ 9 public class Solution { 10 public ListNode addTwoNumbers(ListNode l1, ListNode l2) { 11 ListNode tmp = new ListNode(0); 12 ListNode head = tmp; 13 int carry = 0; 14 while(l1!=null || l2!=null || carry != 0){ 15 int val = ((l1 != null)?l1.val:0) + ((l2!=null)?l2.val:0) + carry; 16 carry = carry/10 + val/10; 17 val %= 10; 18 tmp.next = new ListNode(val); 19 tmp = tmp.next; 20 l1 = l1!=null ? l1.next : l1; 21 l2 = l2!=null ? l2.next : l2; 22 } 23 return head.next; 24 } 25 }