You are given two non-empty linked lists rePResenting two non-negative integers. The most significant digit comes first and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Follow up: What if you cannot modify the input lists? In other Words, reversing the lists is not allowed.
Example:
Input: (7 -> 2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 8 -> 0 -> 7
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) { stack<int> ls1, ls2; while (l1) { ls1.push(l1->val); l1 = l1->next; } while (l2) { ls2.push(l2->val); l2 = l2->next; } int carry = 0; ListNode *r = NULL, *p = r; while (!ls1.empty() || !ls2.empty() || carry) { int a = ls1.empty() ? 0 : ls1.top(), b = ls2.empty() ? 0 : ls2.top(); int sum = a + b + carry; p = new ListNode(sum % 10); p->next = r; r = p; carry = sum / 10; if (!ls1.empty()) ls1.pop(); if (!ls2.empty()) ls2.pop(); } return r; }};新闻热点
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