add two list

src/main/java/list/LintCode_0167_AddTwoNumbers.java

-package list;
-
-// 两个链表相加问题
-//给定两个链表的头节点head1和head2，
-//        认为从左到右是某个数字从低位到高位，返回相加之后的链表
-//        例子     4 -> 3 -> 6        2 -> 5 -> 3
-//        返回     6 -> 8 -> 9
-//        解释     634 + 352 = 986
-// https://www.lintcode.com/problem/167/
-// 笔记见：https://www.cnblogs.com/greyzeng/p/16629407.html
-public class LintCode_0167_AddTwoNumbers {
-    public class ListNode {
-        int val;
-        ListNode next;
-
-        ListNode(int x) {
-            val = x;
-            next = null;
-        }
-    }
-
-    public ListNode addLists(ListNode head1, ListNode head2) {
-        int len1 = listLength(head1);
-        int len2 = listLength(head2);
-        ListNode l = len1 >= len2 ? head1 : head2;
-        ListNode s = l == head1 ? head2 : head1;
-        ListNode curL = l;
-        ListNode curS = s;
-        int carry = 0;
-        ListNode preEnd = l;
-        int sum;
-        while (curS != null) {
-            sum = curL.val + curS.val + carry;
-            carry = sum / 10;
-            curL.val = sum % 10;
-            preEnd = curL;
-            curL = curL.next;
-            curS = curS.next;
-        }
-        while (curL != null) {
-            sum = curL.val + carry;
-            carry = sum / 10;
-            curL.val = sum % 10;
-            preEnd = curL;
-            curL = curL.next;
-        }
-        if (carry != 0) {
-            preEnd.next = new ListNode(carry);
-        }
-        return l;
-    }
-
-    // 求链表长度
-    public int listLength(ListNode head) {
-        int len = 0;
-        while (head != null) {
-            len++;
-            head = head.next;
-        }
-        return len;
-    }
-
-}