归并排序两种实现——代码

递归

#include
#include
#include
#define maxn 10000
void Marge_sort(int ap[],int n);

void Divide(int ap[],int tmp[],int left,int right);

void Combine(int ap[],int tmp[],int l,int r,int rend);
int array[maxn];
//归并排序递归实现 
void Marge_sort(int ap[],int n)        //调整函数接口 
{
	int *tmp=(int *)malloc(sizeof(int)*n);
	Divide(ap,tmp,0,n-1);
}

void Divide(int ap[],int tmp[],int left,int right)  //先分解问题 
{
	int center;
	if(left<right)         //当元素不只有一个时，要先归后并 
	{
		center=(left+right)/2;
		Divide(ap,tmp,left,center);
		Divide(ap,tmp,center+1,right);
		Combine(ap,tmp,left,center+1,right);
	}
}

void Combine(int ap[],int tmp[],int l,int r,int rend)  //合并两个区间,线性表合并 
{
	int len=rend-l+1;
	int lend=r-1;
	int t=l;
	while(l<=lend&&r<=rend)
	{
		if(ap[l]<=ap[r])tmp[t++]=ap[l++];
		else tmp[t++]=ap[r++];
	}
	while(l<=lend)
	{
		tmp[t++]=ap[l++];
	}
	while(r<=rend)
	{
		tmp[t++]=ap[r++];
	}
	int i;
	for(i=0;i<len;i++)ap[rend-i]=tmp[rend-i];
}
int main()
{
	int n,i;
	scanf("%d",&n);
	for(i=0;i<n;i++)scanf("%d",&array[i]);
	Marge_sort(array,n);
	for(i=0;i<n;i++)printf("%d ",array[i]);
	return 0;
} 

非递归

#include
#include
#include
#define maxn 1000010
int array[maxn];
void combine(int ap[],int tmp[],int l,int r,int rend)    //合并数组 
{
	int len=rend-l+1;
	int lend=r-1;
	int t=l;
	while(l<=lend&&r<=rend)
	{
		if(ap[l]<=ap[r])tmp[t++]=ap[l++];
		else tmp[t++]=ap[r++];
	}
	while(l<=lend)
	{
		tmp[t++]=ap[l++];
	}
	while(r<=rend)
	{
		tmp[t++]=ap[r++];
	}
	for(int i=0;i<len;i++)ap[rend-i]=tmp[rend-i];
}
void Combine_hand(int ap[],int tmp[],int n,int len)    //对每一小段进行合并 
{
	int i,j;
	for(i=0;i<=n-2*len;i+=2*len)
	{
		combine(ap,tmp,i,i+len,i+2*len-1);
	}
	if(i+len<n)combine(ap,tmp,i,i+len,n-1);
}
void Marge_sort(int ap[],int n)                      //len的长度慢慢增加 
{
	int *tmp=(int *)malloc(sizeof(int)*n);
	int len=1;
	while(len<n)
	{
		Combine_hand(ap,tmp,n,len);
		len*=2;
		printf("%d",array[0]);
		for(int i=1;i<n;i++)printf(" %d",ap[i]);
		printf("\n");
	}
}
int main()
{
	int n,i;
	scanf("%d",&n);
	for(i=0;i<n;i++)scanf("%d",&array[i]);
	Marge_sort(array,n);
	return 0;
}