链表非降序列插入元素

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
struct node
{
int date;
node *next;
};
node *insert_(int k,node *head)
{
node  * temp=(node *)malloc(sizeof(node));
temp->date=k;
temp->next=NULL;
node *last=head,*it;
int flag=0;
for(it=head->next;it!=NULL;it=it->next )
{
if(temp->date<=it->date)
{
flag=1;
last->next=temp;
temp->next=it;
break;
}
else
last=it;
}
if(flag==0)
{
last->next=temp;
}
return head;
}
void shou(node *head)
{
node *l;
l=head->next;
while(l!=NULL)
{
cout<<l->date<<" ";
l=l->next;
}
cout<<endl;
}
int main()
{
int n,k;
node *head,*l,*p;
head=(node*)malloc(sizeof(node));
while(~scanf("%d",&n))
{
for(int i=0; i<n; i++)
{
p=(node*)malloc(sizeof(node));
cin>>p->date;
p->next=NULL;
if(i==0)
head->next=l=p;
else
{
l->next=p;
l=p;
}
}
shou(head);
cin>>k;
head=insert_(k,head);
shou(head);

}
return 0;
}