собственно код

int left, right;
bool direction;

left = 0;
right = 9;
direction = true;

while(left!=right)
{
    if(direction)
    {
        if(a[right]<0) 
        {
            swap(a[left],a[right]);
            left++;
            direction = false;
        }
    }
    else
    {
        if(a[left]>=0) 
        {
            swap(a[left],a[right]);
            right++;
            direction = true;
        }

    }
}

if(a[left]<0)left++;

if((left==0)||(left==10)) nomad_huita(left);

b = a;
c = b + left;