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2. Add Two Numbers

2024-08-23 09:40:22   222人阅读

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

time complexity O(n)
space complexity O(1)

  1. /**
  2.  * Definition for singly-linked list.
  3.  * struct ListNode {
  4.  *     int val;
  5.  *     ListNode *next;
  6.  *     ListNode(int x) : val(x), next(NULL) {}
  7.  * };
  8.  */
  9. class Solution {
  10. public:
  11.     ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
  12.         ListNode * pHead = new ListNode(0);
  13.         ListNode * pi = pHead;
  14.         int carry = 0;
  15.         while( l1 != NULL || l2 != NULL){
  16.             int sum = (l1==NULL?0:l1->val) + (l2==NULL?0:l2->val) + carry;
  17.             carry = sum / 10;
  18.             pi->next = new ListNode(sum%10);
  19.             pi = pi->next;
  20.             if( l1 != NULL)l1 = l1->next;
  21.             if( l2 != NULL)l2 = l2->next;
  22.         }
  23.         if(carry == 1)
  24.             pi->next = new ListNode(carry);
  25.         return pHead->next;
  26.     }
  27. };



来自为知笔记(Wiz)


2. Add Two Numbers


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