Puzzle: Sort an array of 0's and 1's in one parse.

Question

Is it possible to arrange the array made up of only 1\'s and 0\'s in descending order within one parse without using auxiliary array?
For example: Suppose you have an ar

Answer 1

How about recursion? Simple and elegant, as always.

void countAndRewrite(int arr[], size_t n, size_t *cone, size_t total)
{
    if (n) {
        if (arr[0])
            ++*cone;

        countAndRewrite(arr + 1, n - 1, cone, total);
        arr[0] = total - n < *cone;
    }
}

int main()
{
    int arr[] = { 0, 1, 0, 1, 1, 1, 0 };
    size_t cone = 0;
    countAndRewrite(arr, 7, &cone, 7);
    for (size_t i = 0; i < 7; i++)
    printf("arr[%zu] = %d\n", i, arr[i]);

    return 0;
}