LeetCode(2) Add Two Numbers解题报告

LeetCode(2) Add Two Numbers

问题:

You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

大意:

给定两个非负的整数，这两个数的每位都是逆序存储的。把两个数相加，返回相加后的数（逆序）。

示例:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8

解题方案：

这个题相对简单，从低位相加，有进位加一到高位即可。

    /*    class ListNode {        int val;        ListNode next;        ListNode(int x) {            val = x;        }    }    */    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        ListNode dummyHead = new ListNode(0);        ListNode p = l1, q = l2, curr = dummyHead;        int carry = 0;        while (p != null || q != null) {            int x = (p != null) ? p.val : 0;            int y = (q != null) ? q.val : 0;            int sum = carry + x + y;            carry = sum / 10;            curr.next = new ListNode(sum % 10);            curr = curr.next;            if (p != null)                p = p.next;            if (q != null)                q = q.next;        }        if (carry > 0) {            curr.next = new ListNode(carry);        }        return dummyHead.next;    }