int merge(int x,int y){
	if(!x||!y)return x+y;
	if(pri[x]<pri[y]){
		r[x]=merge(r[x],y);
		pushup(x);
	}
	else{
		l[y]=merge(x,l[y]);
		pushup(y);
	}
}

摘自 CSP-J T2