Mergesort-归并排序

#include<iostream>

using namespace std;

void Merge(intr[],int r1[],int s,int m,int t)
{
inti=s;
intj=m+1;
intk=s;
while(i<=m&&j<=t){
if(r[i]<=r[j]) r1[k++]=r[i++];
elser1[k++]=r[j++];
}
if(i<=m)
while(i<=m)r1[k++]=r[i++];
else
while(j<=t)r1[k++]=r[j++];
for(intl=s;l<=t;l++)
r[l]=r1[l];
}
void MergeSort(intr[],int r1[],int s,int t)
{
if(s==t)r1[s]=r[s];
else{
intm=(s+t)/2;
MergeSort(r,r1,s,m);
MergeSort(r,r1,m+1,t);
Merge(r1,r,s,m,t);
}
}

int main()
{
intr[8]={10,3,5,1,9,34,54,565},r1[8];
MergeSort(r,r1,0,7);
for(intq=0;q<8;q++)
cout<<""<<r[q];
return1;
}

链表结构版：

struct node
{
int data;
node * next;
};

/*
**对两个有序链表进行归并
*/
node*MergeList(node *head1, node *head2)

{
node * tmp;
if(head1 == NULL)

return head2;

if(head2 == NULL)

return head1;

if(head1->data < head2->data)

{
tmp = head1;
head1 = head1->next;

}
else
{
tmp = head2;
head2 = head2->next;

}
tmp->next = MergeList(head1, head2);//经典
return tmp;
}

/*
**归并排序，参数为要排序的链表的头结点，函数返回值为排序后的链表的头结点
*/
node*MergeSort(node *head)

{
if(head == NULL)

return 0;
node * r_head = head;

node *head1 = head;

node* head2 = head;

while(head2->next != NULL &&head2->next ->next!= NULL)

{
head1 = head1->next;

head2 = head2->next->next;

}
if(head1->next ==NULL)/*说明只有一个节点，则返回该节点*/

return r_head;

head2 = head1->next;

head1->next = NULL;

head1 = head;
/*函数MergeList是对两个有序链表进行归并，返回值是归并后的链表的头结点*/

r_head = MergeList(MergeSort(head1),MergeSort(head2));

return r_head;
}