[DP 可并堆维护凸包优化] BZOJ 4585 [Apio2016]烟火表演

垂死梦中惊坐起，膜拜神犇王梦迪

#include
#include
#include
using namespace std;
typedef long long ll;

inline char nc(){
	static char buf[100000],*p1=buf,*p2=buf;
	if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }
	return *p1++;
}

inline void read(int &x){
	char c=nc(),b=1;
	for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;
	for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;
}

const int N=600005;

struct node{
	node *l,*r; ll v;
	node(ll _v=0) { l=NULL; r=NULL; v=_v; }
}nodes[N],*root[N];
int ncnt;
inline int ran(){ static int x=31253125; x+=(x<<4)+1; return x&65536; }
inline node* M(node *p,node *q){
	return (!p||!q)?(!p?q:p):(p->vv?M(q,p):((ran()?p->l=M(p->l,q):p->r=M(p->r,q)),p));
}

int n,m; ll sum;
int d[N],fat[N],w[N];
ll p[N]; int cnt;

int main(){
	freopen("t.in","r",stdin);
	freopen("t.out","w",stdout);
	read(n); read(m);
	for (int i=2;i<=n+m;i++){
		read(fat[i]); read(w[i]);
		sum+=w[i]; d[fat[i]]++;
	}
	for (int i=n+m;i>1;i--){
		ll l=0,r=0;
		if (i<=n){
			while (--d[i])
				root[i]=M(root[i]->l,root[i]->r);
			r=root[i]->v;
			root[i]=M(root[i]->l,root[i]->r);
			l=root[i]->v;
			root[i]=M(root[i]->l,root[i]->r);
		}
		nodes[++ncnt]=node(l+w[i]);
		nodes[++ncnt]=node(r+w[i]);
		root[i]=M(root[i],M(nodes+ncnt,nodes+ncnt-1));
		root[fat[i]]=M(root[fat[i]],root[i]);
	}
	while (d[1]--)
		root[1]=M(root[1]->l,root[1]->r);
	for (int i=1;root[1];i++){  
		p[++cnt]=root[1]->v;
		root[1]=M(root[1]->l,root[1]->r);
	}
	for (int i=1;i<=cnt;i++)  
		sum-=p[i];
	printf("%lld\n",sum);  
	return 0;  
}