兩個鏈表都是有序的,合併它們
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
class Solution {
public:
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
ListNode * pHeader = new ListNode(-1);
ListNode * pCurrent = pHeader;
while(l1 != NULL && l2 != NULL)
{
if(l1->val <= l2->val)
{
pCurrent->next = l1;
l1 = l1->next;
}
else
{
pCurrent->next = l2;
l2 = l2->next;
}
pCurrent = pCurrent->next;
}
// 合併後 l1 和 l2 最多隻有一個還未被合併完,直接將鏈表末尾指向未合併完的鏈表即可
pCurrent->next = l1 == NULL ? l2 : l1;
return pHeader->next;
}
};