Add Two Numbers

最新推荐文章于 2024-08-12 10:14:14 发布

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本文介绍了一种算法，该算法接收两个表示非负整数的链表，并将这两个数相加，返回一个新的链表来表示结果。链表中的数字以逆序方式存储，每个节点包含一个数字。

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

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
        
        int c = 0;
        ListNode* pre = NULL;
        ListNode* res = NULL;
        
        while(l1 || l2){
           
            int v1 = l1?l1->val:0;
            int v2 = l2?l2->val:0;
            int val = v1 + v2 + c;
            
            c = val / 10;
            val = val % 10;
            
            ListNode *node = new ListNode(val); //new node, local variables will be invalidate when the method executed done.
            
            if(!pre){
                pre = node;
                res = pre;                
            }else{
                pre->next = node;
            }
            
            pre = node;
            if(l1)
                l1 = l1->next;
            if(l2)
                l2 = l2->next;
            
        }
        
        if(c != 0){
            ListNode *node = new ListNode(c);
            pre->next = node;
        }
        
        return res;
        
    }
};