https://leetcode.com/problems/merge-two-sorted-lists/
Source
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
ListNode stHead;
ListNode* pstCur = &stHead;
while ((l1!=nullptr) && (l2!=nullptr)) {
if (l1->val < l2->val) {
pstCur->next = l1;
l1=l1->next;
}
else {
pstCur->next = l2;
l2=l2->next;
}
pstCur = pstCur->next;
}
while (l1!=nullptr) {
pstCur->next = l1;
l1=l1->next;
pstCur = pstCur->next;
}
while (l2!=nullptr) {
pstCur->next = l2;
l2=l2->next;
pstCur = pstCur->next;
}
return stHead.next;
}