int random(int possible[],int possmax)
{
	int posssize=sizeof(possible);
	int posssum=0;
	int possrand=rand()%possmax;
	for(int i=0;i<posssize;i++)
	{
		posssum+=possible[i];
		if(posssum>possrand)
		{
			return i;
		}
	}
	return posssize;
} 
random({1,2,3,4},15);//报错