Quick Sort

void quickSortR(int* a, int N) {
    int i = 0, j = N-1;
    int temp, p;
    p = a[N>>1];
    do{
        while ( a[i] < p ) i++;
        while ( a[j] > p ) j--;
        if (i <= j)
        {
            temp = a[i]; a[i] = a[j]; a[j] = temp;
            i++; j--;
        }
    }while(i<=j);
    if ( j > 0 ) quickSortR(a, j+1);
    if ( N-1 > i ) quickSortR(a+i, N-i);
}