版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/jirryzhang/article/details/82263536
ListNode *sortList(ListNode *head) {
//链表归并排序
if(head == nullptr || head->next == nullptr)
return head;
else{
//快慢指针找到中间节点
ListNode *fast = head,*slow = head;
while(fast->next != nullptr && fast->next->next != nullptr){
fast = fast->next->next;
slow = slow->next;
}
fast = slow;
slow = slow->next;
fast->next = NULL;
fast = sortList(head);//前半段排序
slow = sortList(slow);//后半段排序
return merge(fast,slow);
}
}
// merge two sorted list to one
ListNode *merge(ListNode *head1, ListNode *head2)
{
if(head1 == nullptr)
return head2;
if(head2 == nullptr)
return head1;
ListNode *res , *p ;
if(head1->val < head2->val){
res = head1;
head1 = head1->next;
}else{
res = head2;
head2 = head2->next;
}
p = res;
while(head1 != nullptr && head2 != nullptr){
if(head1->val < head2->val){
p->next = head1;
head1 = head1->next;
} else{
p->next = head2;
head2 = head2->next;
}
p = p->next;
}
if(head1 != nullptr)
p->next = head1;
else if(head2 != nullptr)
p->next = head2;
return res;
}