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MergeTwoSortedLists.cpp
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MergeTwoSortedLists.cpp
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#include <vector>
using namespace std;
struct ListNode{
int val;
ListNode *next;
ListNode(int x):val(x),next(nullptr){}
};
class Solution {
public:
/* Sol 0
* Recursive way
*/
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
if(l1 == nullptr) return l2;
if(l2 == nullptr) return l1;
if(l1->val < l2->val){
l1->next = mergeTwoLists(l1->next,l2);
return l1;
}
else{
l2->next = mergeTwoLists(l2->next,l1);
return l2;
}
}
/* Sol 1
* Iterative way
*/
ListNode* mergeTwoLists1(ListNode* l1,ListNode* l2){
ListNode dummy(0);
ListNode *cur = &dummy;
while(l1 != nullptr && l2 != nullptr){
if(l1->val < l2->val){
cur->next = l1;
l1 = l1->next;
}
else{
cur->next = l2;
l2 = l2->next;
}
cur=cur->next;
}
cur->next = (l1==nullptr)?l2:l1;
return dummy.next;
}
};