2. 两数相加
给你两个 非空 的链表,表示两个非负的整数。它们每位数字都是按照 逆序 的方式存储的,并且每个节点只能存储 一位 数字。
请你将两个数相加,并以相同形式返回一个表示和的链表。
你可以假设除了数字 0 之外,这两个数都不会以 0 开头。
示例 1:
输入:l1 = [2,4,3], l2 = [5,6,4]
输出:[7,0,8]
解释:342 + 465 = 807.
示例 2:
输入:l1 = [0], l2 = [0]
输出:[0]
示例 3:
输入:l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
输出:[8,9,9,9,0,0,0,1]
提示:
每个链表中的节点数在范围 [1, 100] 内
0 <= Node.val <= 9
题目数据保证列表表示的数字不含前导零
我的代码
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2){
int temp, count = 0;
struct ListNode* p1 = l1, *p2 =l2,*prev = NULL;
while(p1 && p2){
temp = p1->val + p2->val + count;
if (temp >=10) {count = 1; temp = temp -10;}
else count = 0;
p1->val = temp;
prev = p1; // 保存前一个节点
p1 = p1->next;
p2 = p2->next;
}
if (!p1){
prev->next = p2;
}
while(prev->next){
prev = prev->next;
temp = prev->val + count;
if (temp >=10) {count = 1; temp = temp -10;}
else count = 0;
prev->val = temp;
}
if (count) {
struct ListNode* node = (struct ListNode*)malloc(sizeof(struct ListNode));
prev->next = node;
node->next = NULL;
node->val = 1;
}
return l1;
}
题解:
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
struct ListNode *head = NULL, *tail = NULL;
int carry = 0;
while (l1 || l2) {
int n1 = l1 ? l1->val : 0;
int n2 = l2 ? l2->val : 0;
int sum = n1 + n2 + carry;
if (!head) {
head = tail = malloc(sizeof(struct ListNode));
tail->val = sum % 10;
tail->next = NULL;
} else {
tail->next = malloc(sizeof(struct ListNode));
tail->next->val = sum % 10;
tail = tail->next;
tail->next = NULL;
}
carry = sum / 10;
if (l1) {
l1 = l1->next;
}
if (l2) {
l2 = l2->next;
}
}
if (carry > 0) {
tail->next = malloc(sizeof(struct ListNode));
tail->next->val = carry;
tail->next->next = NULL;
}
return head;
}