归并排序

#define _CRT_SECURE_NO_WARNINGS
#include
#include
using namespace std;
#define MAX 10
int* CreateArray(){

	int *arr = (int*)malloc(sizeof(int)*MAX);
	srand((unsigned int)time(NULL));
	for (int i = 0; i < MAX; i++)
	{
		arr[i] = rand()% MAX;
	}
	return arr;
}
void PrintArray(int *arr,int len){
	for (int i = 0; i < len; i++)
	{
		cout << arr[i] << "";
	}
	cout << endl;
}
//合并算法
void merge(int *arr,int start, int end, int mid, int *temp){

	int i_start = start;
	int i_end = mid;
	int j_start = mid + 1;
	int j_end = end;
	int length = 0;
	while (i_start<=i_end&&j_start<=j_end)
	{
		if (arr[i_start] < arr[j_start])
		{
			temp[length] = arr[i_start];
			length++;
			i_start++;
		}
		else
		{
			temp[length] = arr[j_start];
			length++;
			j_start++;
		}


	}
	//i序列剩下来的
	while (i_start<=i_end)
	{
		temp[length] = arr[i_start];
		length++;
		i_start++;
	}
	while (j_start <= j_end)
	{
		temp[length] = arr[j_start];
		length++;
		j_start++;
	}
	//辅助空间数据覆盖原空间
	for (int i = 0; i < length; i++)
	{
		arr[start + i] = temp[i];
	}

}
void MergeSort(int *arr,int start,int end,int *temp){
	if (start>=end)
	{
		return;
	}
	int mid = (start + end) / 2;
	//分组
	//左半边
	MergeSort(arr, start, mid, temp);
	//右半边
	MergeSort(arr, mid + 1, end, temp);
	//合并
	merge(arr,start,end,mid,temp);
}
void main(void){
	int *arr = CreateArray();
	PrintArray(arr, MAX);
	int *temp = (int*)malloc(sizeof(int)*MAX);
	MergeSort(arr, 0, MAX - 1, temp);
	PrintArray(arr, MAX);
	system("pause");

}