#2 Add Two Numbers

最新推荐文章于 2020-02-23 04:39:50 发布

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#LeetCode #Linked List #Math #C语言

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本文介绍了一个LeetCode上的经典题目——两数相加的链表实现方法。题目要求将两个非负整数以链表形式表示，并以逆序方式存储每个节点的单个数字，最终返回两个数相加的结果作为新的链表。

题目链接：https://leetcode.com/problems/add-two-numbers/

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;
 *     struct ListNode *next;
 * };
 */
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
    int sum = 0;
    struct ListNode* dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode* p = dummy;
    while(l1 != NULL || l2 != NULL) {
        p->next = (struct ListNode* )malloc(sizeof(struct ListNode));
        p = p->next;
        if(l1 != NULL) {
            sum += l1->val;
            l1 = l1->next;
        }
        if(l2 != NULL) {
            sum += l2->val;
            l2 = l2->next;
        }
        p->val = sum % 10;
        sum /= 10;
    }
    if(sum) {
        p->next = (struct ListNode *)malloc(sizeof(struct ListNode));
        p = p->next;
        p->val = sum;
    }
    p->next = NULL;     //尾节点指向空
    p = dummy;
    free(dummy);
    return p->next;
}