【BZOJ 3669】 [Noi2014]魔法森林 LCT维护动态最小生成树

#include <cstdio>
#include <algorithm>
namespace Pre{
inline void read(int &sum){
register char ch=getchar();
for(sum=0;ch<'0'||ch>'9';ch=getchar());
for(;ch>='0'&&ch<='9';sum=(sum<<1)+(sum<<3)+ch-'0',ch=getchar());
}
const int N=50010;
const int M=100010;
const int Inf=0x7f7f7f7f;
int A[M],B[M],ans=Inf,X[M],Y[M],n,m,e[M];
inline bool comp(int a,int b){
return A[a]<A[b];
}
inline int Max(int x,int y){
return x>y?x:y;
}
inline int Min(int x,int y){
return x<y?x:y;
}
}
namespace LCT{
const int MN=150020;
struct Node{
Node *ch[2],*f;
int id,rid;
bool rev;
inline void pushup(){
using Pre::B;
id=B[ch[0]->id]>B[ch[1]->id]?ch[0]->id:ch[1]->id;
id=B[id]>B[rid]?id:rid;
}
inline void pushdown();
}null[MN];
inline void Swap(Node *&a,Node *&b){
Node *c=a;
a=b;
b=c;
}
inline void Node:: pushdown(){
if(!rev)return;
Swap(ch[0],ch[1]);
ch[0]->rev^=1;
ch[1]->rev^=1;
rev=0;
}
inline void Init(){
using namespace Pre;
null->ch[0]=null->ch[1]=null->f=null;
for(int i=1;i<=n;i++)
null[i].ch[0]=null[i].ch[1]=null[i].f=null,null[i].id=null[i].rid=0;
for(int i=n+1;i<=n+m;i++)
null[i].ch[0]=null[i].ch[1]=null[i].f=null,null[i].id=null[i].rid=i-n;
}
inline int get(Node *p){
return p->f->ch[1]==p;
}
inline bool isroot(Node *p){
return p->f->ch[0]!=p&&p->f->ch[1]!=p;
}
inline void rotate(Node *p){
Node *fa=p->f,*pa=fa->f;
int j=get(p);
if(!isroot(fa))pa->ch[get(fa)]=p;
if((fa->ch[j]=p->ch[j^1])!=null)fa->ch[j]->f=fa;
fa->f=p;
p->ch[j^1]=fa;
p->f=pa;
fa->pushup();
p->pushup();
}
inline void spaly(Node *p){
p->pushdown();
for(Node *fa=p->f;!isroot(p);rotate(p),fa=p->f)
if(!isroot(fa)){
fa->f->pushdown(),fa->pushdown(),p->pushdown();
rotate(get(fa)==get(p)?fa:p);
}else
fa->pushdown(),p->pushdown();
}
inline void expose(Node *p){
Node *y=null;
while(p!=null){
spaly(p);
p->ch[1]=y;
p->pushup();
y=p;
p=p->f;
}
}
inline void make_root(Node *p){
expose(p);
spaly(p);
p->rev^=1;
}
inline Node *find_root(Node *p){
expose(p);
spaly(p);
while(p->ch[0]!=null)
p=p->ch[0],p->pushdown();
return p;
}
inline void link(Node *a,Node *b){
make_root(a);
a->f=b;
}
inline void cut(Node *a,Node *b){
make_root(a);
expose(b);
spaly(b);
b->ch[0]->f=null;
b->ch[0]=null;
b->pushup();
}
inline void Link(int a,int b){
link(null+a,null+b);
}
inline void Cut(int a,int b){
cut(null+a,null+b);
}
inline int find(int x){
return find_root(null+x)-null;
}
inline int query(int a,int b){
Node *x=null+a,*y=null+b;
make_root(x);
expose(y);
spaly(y);
return Pre::B[y->id];
}
inline int query_id(int a,int b){
Node *x=null+a,*y=null+b;
make_root(x);
expose(y);
spaly(y);
return y->id;
}
}
inline void Init(){
using namespace Pre;
read(n),read(m);
for(int i=1;i<=m;i++)
read(X[i]),read(Y[i]),read(A[i]),read(B[i]),e[i]=i;
std::sort(e+1,e+m+1,comp);
LCT::Init();
}
inline void Work(){
using namespace Pre;
using LCT::find;
using LCT::query;
using LCT::Link;
using LCT::Cut;
using LCT::query_id;
for(int i=1;i<=m;i++)
if(find(X[e[i]])!=find(Y[e[i]])){
Link(e[i]+n,X[e[i]]),Link(e[i]+n,Y[e[i]]);
if(find(1)==find(n))
ans=Min(query(1,n)+A[e[i]],ans);
}else if(query(X[e[i]],Y[e[i]])>B[e[i]]){
int temp=query_id(X[e[i]],Y[e[i]]);
Cut(temp+n,X[temp]),Cut(temp+n,Y[temp]);
Link(e[i]+n,X[e[i]]),Link(e[i]+n,Y[e[i]]);
if(find(1)==find(n))
ans=Min(ans,query(1,n)+A[e[i]]);
}
}
int main(){
using namespace Pre;
Init(),Work();
printf("%d",ans==Inf?-1:ans);
return 0;
}