C++模板实现归并排序

归并排序的思想是将一个大的序列先进行二分法划分,直到划分到每个子序列只包含一个元素为止. 然后对序列进行依次合并,在合并的过程中实现排序.归并排序是一种典型的外部排序算法,需要额外的辅助空间来完成算法.

算法分析:
1.稳定
2.时间复杂度: O(nlog(n))
3.需要额外辅助空间来实现排序

//Mergesort//1. Stable//2. Time complex O(nlog(n))//3. Need addition space's help (tempArray)//4. In one time merge sort, when low>=high, stoptemplate <typename T, unsigned int size>void Sort<T, size>::mergeSort(T* const sortArray, int low, int high){    if (low >= high)    {    }    else    {        int mid = (low + high) / 2;        mergeSort(sortArray, low, mid);        mergeSort(sortArray, mid + 1, high);        merge(sortArray, low, high);    }    return;}template <typename T, unsigned int size>void Sort<T, size>::merge(T* const sortArray, int low, int high){    T* tempArray = new T[high-low+1];    int mid = (low + high) / 2;    int i = low;    int j = mid + 1;    int tempArrayIndex = 0;    while ((i <= mid) && (j <= high))    {        loopTimes++;        if (sortArray[i] <= sortArray[j])        {            tempArray[tempArrayIndex] = sortArray[i];            i++;            tempArrayIndex++;        }        else        {            tempArray[tempArrayIndex] = sortArray[j];            j++;            tempArrayIndex++;        }    }    if (i > mid)    {        while (j <= high)        {            loopTimes++;            tempArray[tempArrayIndex] = sortArray[j];            j++;            tempArrayIndex++;        }    }    else if (j > high)    {        while (i <= mid)        {            loopTimes++;            tempArray[tempArrayIndex] = sortArray[i];            i++;            tempArrayIndex++;        }    }    //tempArrayIndex = 0;    //for (int i = low; i <= high; i++)    //{    //  sortArray[i] = tempArray[tempArrayIndex];    //  tempArrayIndex++;    //}    memset(&sortArray[low], 0, sizeof(T) * (high-low+1));    memcpy(&sortArray[low], tempArray, sizeof(T) * (high-low+1));    delete[] tempArray;    tempArray = NULL;    return;}