求助归并算法问题

[李万鹏]

请大虾帮忙找一下问题 十分感谢
struct student * guibing(struct student *head1,struct student *head2){
struct student * newhead = NULL,*p3 = NULL;
struct student *p1 = head1,*p2 = head2;
newhead = p3 = head1;
while(p1 != NULL && p2 != NULL){
if(newhead == NULL){
if(p1->number < p2->number){
newhead = p3 = p1;
p1 = p1->next;
}
else{
newhead = p3 = p2;
p2 = p2->next;
}
}
else{
if(p1->number < p2->number){
p3->next = p1;
p3 = p1;
p1 = p1->next;
}
else{
p3->next = p2;
p3= p2;
p2 = p2->next;
}
}
}
p3->next = p1?p1:p2;
return newhead;
}

[李万鹏]

我是问错在哪

[whg01]

newhead = p3 = head1; //while循环上的这句删掉就好了。
因为没有比较head1和head2的大小关系，所以不能设置newhead和p3。
while循环里会处理。

[李万鹏]

还是没有正确结果呀

[李万鹏]

这是我完整的程序 除了归并函数 其他都对
#include <stdio.h>
#include <stdlib.h>
struct student{
int number;
int score;
struct student * next;
};
struct student * creat(){
struct student *head = NULL,*p=NULL,*q=NULL;
p = (struct student *)malloc(sizeof(struct student));
scanf("%d,%d",&p->number,&p->score);
while(p->number != 0){
if(head == NULL)
head = q = p;
else{
q->next = p;
q = p;
}
p = (struct student *)malloc(sizeof(struct student));
scanf("%d,%d",&p->number,&p->score);
}
q->next = NULL;
return head;
}
struct student * guibing(struct student *head1,struct student *head2){
struct student * newhead = NULL,*p3 = NULL;
struct student *p1 = head1,*p2 = head2;
newhead = p3 = head1;
while(p1 != NULL && p2 != NULL){
if(newhead == NULL){
if(p1->number < p2->number){
// newhead = p3 = p1;
p1 = p1->next;
}
else{
newhead = p3 = p2;
p2 = p2->next;
}
}
else{
if(p1->number < p2->number){
p3->next = p1;
p3 = p1;
p1 = p1->next;
}
else{
p3->next = p2;
p3= p2;
p2 = p2->next;
}
}
}
p3->next = p1?p1:p2;
return newhead;
}
void print(struct student *head){
struct student *p = head;
if(head == NULL)
printf("表为空");
else
while(p != NULL){
printf("%d,%d\n",p->number,p->score);
p = p->next;
}
}
int main(){
struct student *head1,* head2,* newhead;
head1 = creat();
head2 = creat();
newhead = guibing(head1,head2);
print(newhead);
system("pause");
return 0;
}

[whg01]

你是怎么输入的？
输入head1时，必须是排好序的。head2也是如此。
归并排序只是对已排好序的2个队列进行合并。如果2个队列内部没有排序，那么归并的结果肯定不对。

[李万鹏]

1,34
3,56
5,78
0
2,56
4,67
是这样输入的呀

[whg01]

明天再看。

[asimay]

感觉p3没有分配内存呢。。。

归并嘛，肯定是新分配的内存单元。