[LeetCode] Add Two Numbers
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
Solutions:
/** * 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) { ListNode *ans = NULL, *end = NULL, *num1 = l1, *num2 = l2; int carry = 0, sum = 0; while(true) { if(num1 != NULL) { if(num2 != NULL) { sum = num1 -> val + num2 -> val + carry; carry = sum / 10; if(ans == NULL) { ans = new ListNode(sum % 10); end = ans; } else { end -> next = new ListNode(sum % 10); end = end -> next; } num1 = num1 -> next; num2 = num2 -> next; } else { sum = num1 -> val + carry; carry = sum / 10; if(ans == NULL) { ans = new ListNode(sum % 10); end = ans; } else { end -> next = new ListNode(sum % 10); end = end -> next; } num1 = num1 -> next; } } else { if(num2 != NULL) { sum = num2 -> val + carry; carry = sum / 10; if(ans == NULL) { ans = new ListNode(sum % 10); end = ans; } else { end -> next = new ListNode(sum % 10); end = end -> next; } num2 = num2 -> next; } else { if(carry == 1) { end -> next = new ListNode(1); end = end -> next; } break; } } } return ans; } };