链表数据结构基础与经典算法实现

链表是数据结构中的重要组成部分，通过对链表的学习可以提高对指针的理解。

1. 链表相加 (Add Two Numbers)

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* cur1 = l1, *cur2 = l2;
        ListNode* newhead = new ListNode(0); // 虚拟头节点
        ListNode* prev = newhead;
        int t = 0;
        while(cur1 || cur2 || t){
            if(cur1){
                t += cur1->val;
                cur1 = cur1->next;
            }
            if(cur2){
                t += cur2->val;
                cur2 = cur2->next;
            }
            prev->next = new ListNode(t % 10);
            prev = prev->next;
            t /= 10;
        }
        prev = newhead->next;
        delete newhead;
        return prev;
    }
};