用C++建立两个带头结点的单链表。输入若干整数，将正整数插入第一个单链表，将负整数插入第二个单链表。在插入前和插入后，两个单链表都要保持递增或相等的次序。最后，显示两个单链表，并销毁它们。在编写程序时，需要注意避免内存泄漏的问题。

以下是用C语言实现的代码：

#include <stdio.h>
#include <stdlib.h>

typedef struct Node {
int data;
struct Node* next;
} Node;

Node* createList() {
Node* head = (Node*)malloc(sizeof(Node));
head->next = NULL;
return head;
}

void insert(Node* head, int data) {
Node* p = head;
while (p->next != NULL && p->next->data < data) {
p = p->next;
}
Node* newNode = (Node*)malloc(sizeof(Node));
newNode->data = data;
newNode->next = p->next;
p->next = newNode;
}

void printList(Node* head) {
Node* p = head->next;
while (p != NULL) {
printf("%d ", p->data);
p = p->next;
}
printf("\n");
}

void destroyList(Node* head) {
Node* p = head;
while (p != NULL) {
Node* q = p->next;
free(p);
p = q;
}
}

int main() {
Node* positiveList = createList();
Node* negativeList = createList();

int n;
while (scanf("%d", &n) != EOF) {
if (n > 0) {
insert(positiveList, n);
} else if (n < 0) {
insert(negativeList, n);
}
}

printList(positiveList);
printList(negativeList);

destroyList(positiveList);
destroyList(negativeList);

return 0;
}