合并两个有序链表
力扣(LeetCode)官网 - 全球极客挚爱的技术成长平台
代码1:
/*** Definition for singly-linked list.* struct ListNode {* int val;* struct ListNode *next;* };*/typedef struct ListNode ListNode;
struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2){//判断链表是否为空if(list1==NULL){return list2;}if(list2==NULL){return list1;}//走到这里说明链表不为空,遍历链表ListNode*cur1=list1;ListNode*cur2=list2;ListNode*newhead,*newtail;newhead=newtail=NULL;while(cur1&&cur2){//1.空链表的情况下:插入的结点就是链表的头结点和尾结点//2.非空链表:插入的结点是链表的新的尾结点,头结点不变if(cur1->val<cur2->val){if(newhead==NULL){newhead=newtail=cur1;}else{newtail->next=cur1;newtail=newtail->next;}cur1=cur1->next;}else{//cur2<=cur1if(newhead==NULL){newhead=newtail=cur2;}else{newtail->next=cur2;newtail=newtail->next;}cur2=cur2->next;}}if(cur1){newtail->next=cur1;}if(cur2){newtail->next=cur2;}return newhead;
}
优化:
/*** Definition for singly-linked list.* struct ListNode {* int val;* struct ListNode *next;* };*/typedef struct ListNode ListNode;
struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2){//判断链表是否为空if(list1==NULL){return list2;}if(list2==NULL){return list1;}//走到这里说明链表不为空,遍历链表ListNode*cur1=list1;ListNode*cur2=list2;ListNode*newhead,*newtail;//newhead为哨兵卫newhead=newtail=(ListNode*)malloc(sizeof(ListNode));// ListNode*newhead,*newtail;// newhead=newtail=NULL;while(cur1&&cur2){//1.空链表的情况下:插入的结点就是链表的头结点和尾结点//2.非空链表:插入的结点是链表的新的尾结点,头结点不变if(cur1->val<cur2->val){// if(newhead==NULL){// newhead=newtail=cur1;// }// else{// newtail->next=cur1;// newtail=newtail->next;// }newtail->next=cur1;newtail=newtail->next;cur1=cur1->next;}else{//cur2<=cur1// if(newhead==NULL){// newhead=newtail=cur2;// }// else{// newtail->next=cur2;// newtail=newtail->next;// }newtail->next=cur2;newtail=newtail->next;cur2=cur2->next;}}if(cur1){newtail->next=cur1;}if(cur2){newtail->next=cur2;}ListNode*returnhead=newhead->next;free(newhead);return returnhead;
}