void OnceSort(int *a, int size);void MergeSort(int *a, int size){    if (size <= 1)        return ;    int which = 2;    int left = size/which;    MergeSort(a, left);    MergeSort(a + left, size - left);    OnceSort(a, size);}void OnceSort(int *a, int size){    int len1 = size/2;    int len2 = size-len1;    int *L = new int[len1];    int *R = new int[len2];    int j = 0;    int k = 0;    int i = 0;        for (i = 0; i < len1; i++)    {        L[i] = a[i];    }    for (i = len1; i < size; i++)    {        R[i-len1] = a[i];    }    for ( i = 0, j = 0, k = 0; k < size; k++)    {        if( i >= len1 || (j < len2 && L[i] > R[j] ))        {            a[k] = R[j];            j++;        }        else        {            a[k] = L[i];            i++;        }    }    delete []L;    delete []R;}