/*
 * Pick a weighted item from a list of weighted numbers
 * Args:
 * const int items[]: The item array to pick from. The element value holds the weighted number
 * const int len: the length ofthe array
 * 
 * NOTE: arrays decay into pointers when passed into functions, so array length can't be calculated in the function.
 * calculate the length outside the function and pass it in as an argument.
 */
int PickWeightedItem(const int items[], const int len)
{
    int sum = 0;
    int i = 0;
    for(i = 0; i < len; i++)
    {
        sum += items[i];
    }
    srand(time(NULL));
    int r = rand() % sum;
    for(i = 0; i < len; i++)
    {
        if(r < items[i])
        {
            break;
        }
        r -= items[i];
    }
    return i;
}