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
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { * val = x; * next = null; * } * } */ public class Solution { public ListNode addTwoNumbers(ListNode l1, ListNode l2) { if (l1==null) { return l2; } if (l2==null) { return l1; } ListNode tail=null,p1=l1,p2=l2; //进位的数字 int add = 0; ListNode head = null; while (p1!=null && p2!=null) { int sum = p1.val+p2.val+add; add = (sum)/10; if (tail==null) { tail = new ListNode((sum)%10); head = tail; } else { tail.next = new ListNode((sum)%10); tail = tail.next; } p1 = p1.next; p2 = p2.next; } while (p1!=null) { int sum = p1.val+add; add = (sum)/10; tail.next = new ListNode((sum)%10); tail = tail.next; p1 = p1.next; } while (p2!=null) { int sum = p2.val+add; add = (sum)/10; tail.next = new ListNode((sum)%10); tail = tail.next; p2 = p2.next; } //最后一位 如果还有进位,需要加一位 if (add!=0) { tail.next = new ListNode(add); } return head; } }