Question

题目内容

解题思路

递归。

代码实现

/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

const dfs = (
  l1: ListNode | null,
  l2: ListNode | null,
  carry: number = 0
): ListNode => {
  if (!l1 && !l2 && carry === 0) {
    return null;
  }
  const value1 = l1?.val ?? 0;
  const value2 = l2?.val ?? 0;
  const sum = value1 + value2 + carry;
  const node = new ListNode(sum % 10);
  node.next = dfs(l1?.next ?? null, l2?.next ?? null, Math.floor(sum / 10));
  return node;
};
const addTwoNumbers = (
  l1: ListNode | null,
  l2: ListNode | null
): ListNode | null => {
  return dfs(l1, l2, 0);
};