归并排序

void mergesort(int []array1, int low, int high)

{

if (low < high)

{

int middle = (low + high) / 2;

mergesort(array1, low, middle);//排序左半部分

mergesort(array1, middle + 1, high);//排序右半部分

merge(array1, low, middle, high);//归并

}

}

void merge(int []array1, int low, int middle, int high)

{

int helper[]=new int[array1.length];

/*将数组左右两半拷贝到helper数组中*/

for (int i = low; i <= high; i++)

{

helper[i] = array1[i];

}

int helperLeft = low;

int helperRight = middle + 1;

int current = low;

/*迭代访问helper数组，比较左右两半的元素，

并将较小的元素复制到原先的数组中*/

while (helperLeft <= middle&&helperRight <= high)

{

if (helper[helperLeft] <= helper[helperRight])

{

array1[current] = helper[helperLeft];

helperLeft++;

}

else

{

array1[current] = helper[helperRight];

helperRight++;

}

current++;

}

/*将数组左半部分剩余元素复杂到目标数组中*/

int remaining = middle - helperLeft;

for (int i = 0; i <= remaining; i++)

{

array1[current + i] = helper[helperLeft + i];

}

}

public static void mergesort(int[] array1)

{

int[] helper = new int[array1.length];

mergesort(array1, helper, 0, array1.length - 1);

}




c++版：

#include<iostream>

using namespace std;

void merge(int array1[], int low, int middle, int high)

{

int len = high - low+1;

int *helper = new int[len];

/*将数组左右两半拷贝到helper数组中*/

for (int i = low; i <= high; i++)

{

helper[i] = array1[i];

}

int helperLeft = low;

int helperRight = middle + 1;

int current = low;

/*迭代访问helper数组，比较左右两半的元素，

并将较小的元素复制到原先的数组中*/

while (helperLeft <= middle&&helperRight <= high)

{

if (helper[helperLeft] <= helper[helperRight])

{

array1[current] = helper[helperLeft];

helperLeft++;

}

else

{

array1[current] = helper[helperRight];

helperRight++;

}

current++;

}

/*将数组左半部分剩余元素复杂到目标数组中*/

int remaining = middle - helperLeft;

for (int i = 0; i <= remaining; i++)

{

array1[current + i] = helper[helperLeft + i];

}

}

void mergesort(int array1[], int low, int high)

{

if (low < high)

{

int middle = (low + high) / 2;

mergesort(array1, low, middle);//排序左半部分

mergesort(array1, middle + 1, high);//排序右半部分

merge(array1, low, middle, high);//归并

}

}

void main()

{

int n = 6;

int *array1 = new int
;

cout << "please input the number:" << endl;

for (int i = 0; i < n; ++i)

{

cin>> array1[i];

}

mergesort(array1, 0, n- 1);

for (int i = 0; i < n; ++i)

{

cout << array1[i];

}

system("pause");

}