C语言实现八种基本排序（二）

#include <stdio.h>
//#include <stdlib.h>
using namespace std;
void merge(int *a,int *temp,int lPos,int rPos,int rEnd)
{
int i,lEnd,tempPos,cout;
lEnd = rPos - 1;
tempPos = lPos;
cout = rEnd - lPos + 1;
while(lPos <= lEnd && rPos <= rEnd)
{
if(a[lPos] <= a[rPos])
temp[tempPos++] = a[lPos++];
else
temp[tempPos++] = a[rPos++];
}
if(lPos <= lEnd)
temp[tempPos++] = a[lPos++];
if(rPos <= rEnd)
temp[tempPos++] = a[rPos++];
for(i = 0;i < cout;i++,rEnd--)
{
a[rEnd] = temp[rEnd];
}
}
void msort(int *a, int *temp, int low, int high)
{
if(low >= high)
return;
int mid = (low + high) / 2;
msort(a, temp, low, mid);
msort(a, temp, mid + 1, high);
merge(a, temp, low, mid + 1, high);
}
void merge_sort(int *a, int len)
{
int *temp = NULL;
temp = new int[len];
//temp = (int *)malloc(sizeof(int) * len);
if(temp != NULL)
{
msort(a, temp, 0, len - 1);
//free(temp);
delete [] temp;
}
}
void print_array(int *a, int len)
{
int i;
for(i = 0; i < len;i++)
{
printf("%d ", a[i]);
}
printf("/n");
}
int main()
{
int a[] = {8,0,3,4,2,1,5,6,9,7};
print_array(a, 10);
merge_sort(a, 10);
print_array(a, 10);
return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void print_array(int *a, int len)
{
int i;
for(i = 0;i < len;i++)
{
printf("%d ", a[i]);
}
printf("/n");
}
//this is down to up merge method.
//arg lPos and rPos are the begin of the two part,
//and arg step stand by the cout of each part,
//and arg len is the length of the a[].
void merge(int *a, int lPos, int rPos, int step, int len)
{
int len_right, index, lEnd, rEnd;

//the length of right part should be compute.
if(rPos + step - 1 >= len - 1)
len_right = len - rPos;
else
len_right = step;
//index is used to remember the lPos to copy from temp[].
index = lPos;
lEnd = rPos - 1;
rEnd = rPos + len_right - 1;
int *temp = (int *)malloc(sizeof(int) * (step + len_right));
int i = 0;
while(lPos <= lEnd && rPos <= rEnd)
{
if(a[lPos] <= a[rPos])
temp[i++] = a[lPos++];
else
temp[i++] = a[rPos++];
}
while(lPos <= lEnd)
temp[i++] = a[lPos++];
while(rPos <= rEnd)
temp[i++] = a[rPos++];

int j;
for(j = 0;j < i;j++)
{
a[index + j] = temp[j];
}
free(temp);
}
//the step is from 1 to until len.
void merge_sort(int *a, int len)
{
int step = 1;
while(step < len)
{
int i;

for(i = 0;i <= (len - step - 1);i += (2 * step))
{
merge(a, i, i + step, step, len);
}

step *= 2;
}
}
int main()
{
int a[] = {2,4,8,0,1,3,7,5,6,9};
print_array(a, 10);
merge_sort(a, 10);
print_array(a, 10);
return 0;
}