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
1 /** 2 * Definition for singly-linked list. 3 * public class ListNode { 4 * int val; 5 * ListNode next; 6 * ListNode(int x) { 7 * val = x; 8 * next = null; 9 * } 10 * } 11 */ 12 public class Solution { 13 public ListNode addTwoNumbers(ListNode l1, ListNode l2) { 14 if(null == l1) 15 return l2; 16 if(null == l2) 17 return l1; 18 ListNode head = new ListNode(0); 19 ListNode ptr = head; 20 int carry = 0; //进位 21 while(null != l1 && null != l2){ 22 ListNode temp = new ListNode(l1.val + l2.val); 23 temp.next = null; 24 ptr.next = temp; 25 ptr = ptr.next; 26 l1 = l1.next; 27 l2 = l2.next; 28 } 29 while(null != l1){ 30 ListNode temp = new ListNode(l1.val); 31 ptr.next = temp; 32 temp.next = null; 33 ptr = ptr.next; 34 l1 = l1.next; 35 } 36 while(null != l2){ 37 ListNode temp = new ListNode(l2.val); 38 ptr.next = temp; 39 temp.next = null; 40 ptr = ptr.next; 41 l2 = l2.next; 42 } 43 //开始进位 44 ptr = head.next; 45 while(null != ptr){ 46 ptr.val = ptr.val + carry; 47 carry = ptr.val / 10; 48 ptr.val %= 10; 49 ptr = ptr.next; 50 } 51 if(1 == carry){ 52 ptr = head.next; 53 while(null != ptr.next) 54 ptr = ptr.next; 55 ListNode temp = new ListNode(1); 56 temp.next = null; 57 ptr.next = temp; 58 } 59 60 return head.next; 61 } 62 }