quick_sort

void quick_sort(int q[], int l, int r)
{
    if(l >= r)  return;

    int x = q[l + r >> 1], i = l - 1, j = r + 1;
    while(i < j){
        do i++; while(q[i] < x);
        do j--; while(q[j] > x);
        if(i < j) 
            swap(q[i], q[j]);
    }

    quick_sort(q, l, j);
    quick_sort(q, j+1, r);
}

merge_sort

void merge_sort(int q[], int l, int r)
{
    if(l >= r)  return;
    int mid = l + r >> 1;
    merge_sort(q, l, mid), merge_sort(q, mid + 1, r);
    int k = 0, i = l, j = mid + 1;
    while(i <= mid && j <= r)
        if(q[i] < q[j]) tmp[k++] = q[i++];
        else tmp[k++] = q[j++];
    while(i <= mid) tmp[k++] = q[i++];
    while(j <= r) tmp[k++] = q[j++];

    for(i = l, j = 0; i <= r; i++, j++)
        q[i] = tmp[j];
}