Add Two Numbers

思路：

/** * 解决思路： * 1.判断链表是否为空 * 2.判断链表长度是否相等 * 3.相加的时候判断两个值之和是否大于10 * */

package com.example.lib2;

public class myClass {

static class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}

public static void main(String[] args) { ListNode l1 =  new ListNode(2); ListNode l2 =  new ListNode(4); ListNode l3 =  new ListNode(3);l1.next = l2;l2.next = l3; ListNode l5 =  new ListNode(5);ListNode l6 =  new ListNode(6);ListNode l7 =  new ListNode(4);    l5.next = l6;    l6.next = l7;    ListNode l9 = null;    ListNode addNode = Solution.addTwoNumbers(l1,l5);    while (addNode != null ) {        System.out.println(addNode.val);        addNode = addNode.next;    }}/** * 解决思路： * 1.判断链表是否为空 * 2.判断链表是否相等 * 3.相加的时候判断两个值之和是否大于10 * * 1 3 5 7 * 2 4 6 */static class Solution {    public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {        if (l1 == null) {            return l2;        }else if (l2 == null) {            return l1;        }        ListNode head = new ListNode(-1);        ListNode current = head;        int up = 0;        while(l1 != null && l2 != null) {            // 2 4 3      5 6 4            int value = (l1.val +l2.val +up) % 10;            ListNode node =  new ListNode(value);            up = (l1.val +l2.val)/10;            current.next = node;            current = current.next;            l1 = l1.next;            l2 = l2.next;        }        while (l1 != null) {            ListNode node =  new ListNode(l1.val);            current.next = node;            current = current.next;            l1 = l1.next;        }        while (l2 != null) {            ListNode node =  new ListNode(l2.val);            current.next = node;            current = current.next;            l2 = l2.next;        }        return head.next;    }}

}