Given a non-negative number represented as a singly linked list of digits, plus one to the number.
The digits are stored such that the most significant digit is at the head of the list.
Example:
Input: 1->2->3 Output: 1->2->4
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Solution { public ListNode plusOne(ListNode head) { if(head == null) return head; ListNode l = new ListNode(0); ListNode dummy = l; ListNode reHead = reverseList(head); int carry = 1; int digit = 0; ListNode cur = reHead; while(cur != null || carry != 0){ int index = (cur == null)? 0 : cur.val ; digit = (index + carry) % 10; carry = (index + carry) / 10; l.next = new ListNode(digit); l = l.next; if(cur != null) cur = cur.next; } return reverseList(dummy.next); } public ListNode reverseList(ListNode head){ if(head == null || head.next == null) return head; ListNode dummy = new ListNode(0); dummy.next = head; ListNode cur = head.next; while(cur != null){ head.next = cur.next; cur.next = dummy.next; dummy.next = cur; cur = head.next; } return dummy.next; } }