两数和 -链表

https://leetcode-cn.com/problems/add-two-numbers/

 

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
if (l1 == null) return l2;
if (l2 == null) return l1;

ListNode dummyHead = new ListNode(0);
ListNode last = dummyHead;
// 进位值
int carry = 0;
while (l1 != null || l2 != null) {
int v1 = 0;
if (l1 != null) {
v1 = l1.val;
l1 = l1.next;
}
int v2 = 0;
if (l2 != null) {
v2 = l2.val;
l2 = l2.next;
}
int sum = v1 + v2 + carry;
// 设置进位值
carry = sum / 10;
// sum的个位数作为新节点的值
last.next = new ListNode(sum % 10);
last = last.next;
}

// 检查最后的进位
if (carry > 0) {
// carry == 1
last.next = new ListNode(carry);
}

return dummyHead.next;
}