链表拼接.c

#include <stdio.h>
#include <stdlib.h>
struct ListNode {
int data;
struct ListNode *next;
};
struct ListNode *createlist(); /*裁判实现，细节不表*/
struct ListNode *mergelists(struct ListNode *list1, struct ListNode *list2);
void printlist( struct ListNode *head )
{
struct ListNode *p = head;
while (p) {
printf("%d ", p->data);
p = p->next;
}
printf("\n");
}
int main()
{
struct ListNode *list1, *list2;

list1 = createlist();
list2 = createlist();
list1 = mergelists(list1, list2);
printlist(list1);

return 0;
}
struct ListNode *createlist()
{
struct ListNode *head = NULL, *tail = NULL;
int num;

// 读入数字直到-1
while (scanf("%d", &num) == 1 && num != -1) {
struct ListNode *node = (struct ListNode *)malloc(sizeof(struct ListNode));
node->data = num;
node->next = NULL;

if (head == NULL) {
head = node;
tail = node;
} else {
tail->next = node;
tail = node;
}
}

return head;
}
struct ListNode *mergelists(struct ListNode *list1, struct ListNode *list2)
{
if (list1 == NULL) return list2;
if (list2 == NULL) return list1;
struct ListNode *head=NULL,*p,*tail=NULL;
if (list1->data <= list2->data) {
head = list1;
list1 = list1->next;
} else {
head = list2;
list2 = list2->next;
}
tail = head;
while(list1!=NULL&&list2!=NULL){
if(list1->data<=list2->data){
tail->next=list1;
list1=list1->next;
}
else{
tail->next=list2;
list2=list2->next;
}
tail=tail->next;
}
if(list1!=NULL)
tail->next=list1;
else
tail->next=list2;
return head;
}