这是我合并两个排序列表的代码。问题在于合并列表功能以及我在没有调试的情况下启动，它会停止。
#include <iostream>
using namespace std;
class node {
private:
double num;
node *link;
public:
node() { }
node(double m, node *n) { num = m; link = n; }
node* getlink() { return link; }
double getdata() { return num; }
void setdata(double m) { num = m; }
void setlink(node* n) { link = n; }
};
typedef node* nodeptr;
void insertnode(nodeptr& head, double m);
void printlist(nodeptr head);
nodeptr mergelists(nodeptr& head1, nodeptr& head2);
void reverselist(nodeptr& head);
nodeptr search(nodeptr head, double searchterm);
void insert(nodeptr afterme, double newdata);
int main()
{
double input;
nodeptr head1 = NULL; // Pointer to the head of List #1
nodeptr head2 = NULL; // Pointer to the head of List #2
nodeptr temp;
// Part 1 - Create two sorted lists
cout << "-------------------------------------" << endl;
cout << "CREATE LIST #1: " << endl;
cout << "-------------------------------------" << endl;
do {
cout << "Enter value (0 to quit): ";
cin >> input;
// Insert the "input" value into the list
insertnode(head1, input);
} while (input != 0);
cout << "-------------------------------------" << endl;
cout << "CREATE LIST #2: " << endl;
cout << "-------------------------------------" << endl;
do {
cout << "Enter value (0 to quit): ";
cin >> input;
// Insert the "input" value into the list
insertnode(head2, input);
} while (input != 0);
// Part 1 - Print the lists to make sure that they are correct.
printlist(head1);
printlist(head2);
// Part 2 - Merge the two lists and display the new merged list
cout << "Merge lists: " << endl;
temp = mergelists(head1, head2);
printlist(temp);
// Part 3 - Reverse the merged list and then display it
return 0;
}
nodeptr search(nodeptr head, double searchterm)
{
nodeptr p = head;
nodeptr q = head->getlink();
if (p == NULL)
return NULL;
else
{
/*set p from beginning, q is the next node of p
*while q is not NULL, search until the 'searchterm' < value of q
*if q is NULL, means the 'searchterm' larger than all element in the linked list, p is the last position, so just attatch the new node after the last node.
*if q is not NULL and 'q->getdata() < searchterm' means, the 'searchterm' > p and < q, so put it in between p and q.
*for both cases, the position is after the p node.
*/
while (p != NULL)
{
q = p->getlink();
while (q != NULL && q->getdata() < searchterm)
{
p = p->getlink();
q = q->getlink();
}
return p;
}
}
}
void insertnode(nodeptr& head, double m)
{
// CASE 1 - List is empty
if (head == NULL)
{
head = new node(m, NULL);
}
// CASE 2 - List is not empty and new value is < 1st value
else if (m < head->getdata())
{
head = new node(m, head);
}
// CASE 3 - List is not empty and new value goes inside list
else
{
// search for correct location - notes on Search
nodeptr afterme = search(head,m);
// insert at this location -- see notes on insert inside list
nodeptr temp;
temp = new node(m, afterme->getlink());
afterme->setlink(temp);
}
}
void printlist(nodeptr head)
{
nodeptr p;
p = head;
while (p != NULL)
{
cout << p->getdata() << endl;
p = p->getlink();
}
}
//问题在这里
nodeptr mergelists(nodeptr& head1, nodeptr& head2)
{
if (head1 == NULL)
return head2;
if (head2 == NULL)
return head1;
nodeptr p1 = head1;
nodeptr p2 = head2;
nodeptr head = NULL;
nodeptr temp = head;
while (head1 != NULL&&head2 != NULL)
{
if (head == NULL)
{
if (p1->getdata() < p2->getdata() || p1->getdata() == p2->getdata())
{
head = p1;
p1 = p1->getlink();
}
else
{
head = p2;
p2 = p2->getlink();
}
}
else
{
if (p1->getdata() < p2->getdata() || p1->getdata() == p2->getdata())
{
temp = p1;
temp->setlink(p1);
p1 = p1->getlink();
}
else
{
temp = p2;
temp->setlink(p2);
p2 = p2->getlink();
}
temp = temp->getlink();
}
}
if (p1 != NULL){
while (p1 != NULL)
{
temp->setlink(p1);
p1 = p1->getlink();
temp = temp->getlink();
}
}
if (p2 != NULL)
{
while (p2 != NULL)
{
temp->setlink(p2);
p2 = p2->getlink();
temp = temp->getlink();
}
}
return head;
}
这是我输出的图像： enter image description here
答案 0 :(得分：0)
nodeptr mergelists(nodeptr& head1, nodeptr& head2)
{
if (head1 == NULL)
return head2;
if (head2 == NULL)
return head1;
nodeptr p1 = head1;
nodeptr p2 = head2;
nodeptr head = NULL;
nodeptr temp;
while (p1 != NULL && p2 != NULL) //here p1 and p2 should be checked for NULL
{
if (head == NULL)
{
if (p1->getdata() <= p2->getdata())
{
head = p1;
p1 = p1->getlink();
}
else
{
head = p2;
p2 = p2->getlink();
}
temp=head; // point temp to head
}
else
{
if (p1->getdata() <= p2->getdata())
{
// temp = p1; // this should be removed
temp->setlink(p1); //the temp's link should be set to p1
p1 = p1->getlink();
}
else
{
// temp = p2;
temp->setlink(p2); //temp's link should be set to p2
p2 = p2->getlink();
}
temp = temp->getlink();
}
}
if (p1 != NULL){
temp->setlink(p1); //here you can remove the while loop
}
if (p2 != NULL)
{
temp->setlink(p2);
}
return head;
}
在你的main函数中还有一个建议，在读取输入时使用while循环而不是while，因为在退出之前0也会被添加到列表中。我猜你不想要那个。