Question

Solution

题目大意：两个链表对应的元素相加，满10进1，反两个链表相加后的链表

思路：同时遍历两个链表，同时构造相加后的链表，满10进1，用一个数来记录进位

Java实现：

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {    ListNode ans = new ListNode(0);    ListNode curL1 = l1;    ListNode curL2 = l2;    ListNode curAns = ans;    int last = 0;    ListNode curAnsPre = ans;    while (curL1 != null || curL2 != null) {        int valL1 = 0;        int valL2 = 0;        if (curL1 != null) {            valL1 = curL1.val;            curL1 = curL1.next;        }        if (curL2 != null) {            valL2 = curL2.val;            curL2 = curL2.next;        }        curAns.val = valL1 + valL2 + last;        if (curAns.val >= 10) {            curAns.val -= 10;            last = 1;        } else {            last = 0;        }        curAns.next = new ListNode(1);        curAnsPre = curAns;        curAns = curAns.next;    }    curAnsPre.next = last == 0 ? null : curAnsPre.next;    return ans;}