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• 原题连接：2. 两数相加

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1- 思路

思路

分为几个步骤 ①数据结构：遍历指针,进位符、②遍历两个链表、③处理最后的进位符

• 1- 数据结构
  • 定义 curA 和 curB 用来遍历两个链表
  • 定义 carry 记录进位
• 2- 遍历两个链表
  • 通过中间变量，读取，若当前节点不为 null则读取值
  • 计算当前 nowNode 值
  • 计算进位值 carry
• 3- 处理最终结果
  • 判断是否有进位值

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2- 实现

⭐2. 两数相加——题解思路

class Solution {public ListNode addTwoNumbers(ListNode l1, ListNode l2) {ListNode curA = l1;ListNode curB = l2;ListNode dummyHead = new ListNode(-1);ListNode cur = dummyHead;int carry = 0;while(curA!=null || curB!=null){int v1 = curA==null? 0:curA.val;int v2 = curB==null? 0:curB.val; int sum = v1+v2+carry;carry = sum/10;int now = sum%10;ListNode newNode = new ListNode(now);cur.next = newNode;cur = cur.next;if(curA!=null) curA = curA.next;if(curB!=null) curB = curB.next;}if(carry!=0){cur.next = new ListNode(carry);}return dummyHead.next;}
}

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3- ACM 实现

public class twoSum {public static class ListNode {int val;ListNode next;ListNode(int x) {val = x;next = null;}}public static ListNode twoSum(ListNode head1,ListNode head2){ListNode curA = head1;ListNode curB = head2;ListNode dummyHead = new ListNode(-1);ListNode cur = dummyHead;int carry = 0;while(curA!=null || curB!=null){int val1 = curA == null? 0: curA.val;int val2 = curB == null? 0: curB.val;int nowNode = (val1+val2+carry)%10;carry = (val1+val2+carry)/10;cur.next = new ListNode(nowNode);cur = cur.next;if(curA!=null) curA = curA.next;if(curB!=null) curB = curB.next;}return dummyHead.next;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);
// 读取第一个链表的节点数量int n1 = sc.nextInt();ListNode head1 = null, tail1 = null;for (int i = 0; i < n1; i++) {int val = sc.nextInt();ListNode newNode = new ListNode(val);if (head1 == null) {head1 = newNode;tail1 = newNode;} else {tail1.next = newNode;tail1 = newNode;}}// 读取第二个链表的节点数量int n2 = sc.nextInt();ListNode head2 = null, tail2 = null;for (int i = 0; i < n2; i++) {int val = sc.nextInt();ListNode newNode = new ListNode(val);if (head2 == null) {head2 = newNode;tail2 = newNode;} else {tail2.next = newNode;tail2 = newNode;}}ListNode forRes = twoSum(head1,head2);while (forRes!=null){System.out.print(forRes.val + " ");forRes = forRes.next;}}
}