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
链表的遍历，仅仅须要一遍就可以。public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode head=null; ListNode last = null; int flag = 0; while(l1!=null&&l2!=null){ int temp; temp = l1.val + l2.val + flag; if (temp >= 10) { temp = temp - 10; flag = 1; } else { flag = 0; } if(head == null){ head = new ListNode(temp); last = head; }else{ ListNode cur = new ListNode(temp); last.next = cur; last = cur; } l1 = l1.next; l2 = l2.next; } while(l1 != null){ if(flag == 1){ int temp = l1.val + 1; if(temp >= 10){ flag = 1; temp = temp -10; }else{ flag = 0; } if(head == null){ head = new ListNode(temp); last = head; }else{ ListNode cur = new ListNode(temp); last.next = cur; last = cur; } l1 = l1.next; }else{ last.next = l1; break; } } while(l2 != null){ if(flag == 1){ int temp = l2.val + 1; if(temp >= 10){ flag = 1; temp = temp -10; }else{ flag = 0; } if(head == null){ head = new ListNode(temp); last = head; }else{ ListNode cur = new ListNode(temp); last.next = cur; last = cur; } l2 = l2.next; }else{ last.next = l2; break; } } if(flag == 1){ ListNode lnTemp = new ListNode(1); last.next = lnTemp; } return head; }
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原文：http://www.cnblogs.com/mengfanrong/p/3896681.html