Lvat_s Blog

怎么说呢……神奇的二分

每次把白色边加上一个二分的权值，再做最小生成树

如果大于need条边就说明加上的权值太小了需要增大

反之亦然(因为题目保证有解，所以必然会存在这样的一个权值)

注意排序时权值相等时白色边放在前面

#include<cstdio>
#include<algorithm>
using namespace std;

int V,E,need,f[100005],test=0,ne=0;

struct Edge{
int a,b,v,co;
friend bool operator<(Edge a,Edge b){
return a.v==b.v?a.co<b.co:a.v<b.v;
}
}e[100005];

int Find(int x){return x==f[x]?x:f[x]=Find(f[x]);}
void Union(int sa,int sb){
if(sa<sb)f[sb]=sa;
else f[sa]=sb;
}

int Check(int ans){
test=ne=0;
for(int i=1;i<=V;i++)f[i]=i;
for(int i=1;i<=E;i++){
	if(!e[i].co)e[i].v+=ans;
}
sort(e+1,e+E+1);
for(int i=1;i<=E;i++){
	if(Find(e[i].a)!=Find(e[i].b)){
		Union(Find(e[i].a),Find(e[i].b));
		test+=e[i].v;
		if(!e[i].co)ne++;
	}
}
for(int i=1;i<=E;i++){
	if(!e[i].co)e[i].v-=ans;
}
return ne>=need;
}

int main(){
freopen("2654.in","r",stdin);
freopen("2654.out","w",stdout);
scanf("%d %d %d",&V,&E,&need);
for(int i=1;i<=E;i++){
	scanf("%d %d %d %d",&e[i].a,&e[i].b,&e[i].v,&e[i].co);
	e[i].a++;
	e[i].b++;
}
int l=-105,r=105,ans;
while(l<=r){
	int mid=l+r>>1;
	if(Check(mid)){ans=test-need*mid;l=mid+1;}
	else r=mid-1;
}
printf("%d\n",ans);
return 0;
}

最大流

拆点，男孩和女孩各拆成2个点ix,iy,jx,jy，互相喜欢ix->jx:1 不互相喜欢iy->jy:1

然后ix->iy=k,jy->jx=k,S->ix=ans,jy->T=ans

枚举ans跑最大流，不满流答案就是ans-1

#include<cstdio>
#include<queue>
#include<algorithm>
#include<cstring>
using namespace std;
 
int en,n,k,level[1005],S,T,cur[1005],POINT_N,h[1005];
char s[55][55];
 
struct Edge{
int b,f,back,next;
}e[1000005];
 
void AddEdge(int sa,int sb,int sc){
e[++en].b=sb;
e[en].f=sc;
e[en].back=en+1;
e[en].next=h[sa];
h[sa]=en;
swap(sa,sb);
e[++en].b=sb;
e[en].f=0;
e[en].back=en-1;
e[en].next=h[sa];
h[sa]=en;
}
 
int BFS(){
queue<int> Q;
Q.push(S);
memset(level,0,sizeof(level));
level[S]=1;
while(!Q.empty()){
    int u=Q.front();
    Q.pop();
    for(int i=h[u];i;i=e[i].next){
        int v=e[i].b;
        if(level[v] || !e[i].f)continue;
        level[v]=level[u]+1;
        Q.push(v);
    }
}
return level[T];
}
 
int DFS(int u,int flow){
if(u==T)return flow;
int f=flow;
for(int &i=cur[u];i;i=e[i].next){
    int v=e[i].b,fl;
    if(level[v]==level[u]+1 && e[i].f && (fl=DFS(v,min(f,e[i].f)))){
        e[i].f-=fl;
        e[e[i].back].f+=fl;
        f-=fl;
        if(f==0)return flow;
    }
}
return flow-f;
}
 
int Dinic(){
int ans=0;
while(BFS()){
    for(int i=1;i<=POINT_N;i++)cur[i]=h[i];
    ans+=DFS(S,2100000000);
}
return ans;
}
 
int main(){
freopen("1305.in","r",stdin);
freopen("1305.out","w",stdout);
scanf("%d %d",&n,&k);
for(int i=1;i<=n;i++)scanf("%s",s[i]+1);
S=4*n+1;
T=4*n+2;
POINT_N=4*n+2;
int ans=1;
while(ans<=1000){
    memset(h,0,sizeof(h));
    for(int i=1;i<=n;i++){
        AddEdge(i,i+n,k);
        AddEdge(i+3*n,i+2*n,k);
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(s[i][j]=='Y'){
                AddEdge(i,j+2*n,1);
            }
            else {
                AddEdge(i+n,j+3*n,1);
            }
        }
    }
    for(int i=1;i<=n;i++){
        AddEdge(S,i,ans);
        AddEdge(i+2*n,T,ans);
    }
    int an=Dinic();
    //printf("%d\n",ans);
    if(an<ans*n){printf("%d\n",ans-1);return 0;}
    ans++;
}
return 0;
}


这题有2问

第一问SPFA

第二问先从1->n 求一遍最短路，再从n->1求一遍最短路，然后判定每条边是否可能在最短路上

即D[e[i].a]+Di[e[i].b]+e[i].t==ans

注意每条边的反向边也需要判断一下

然后跑一遍最大流就行了（最小割=最大流）

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;

int h[505],n,m,en,en1,D[505],Di[505],flag[505],S,T,cur[505];

struct Es{
int a,b,t,c;
}E[200005];

struct Edge1{
int b,v,next;
}e1[300005];

struct Edge{
int b,f,next,back;
}e[300005];

void AddEdge1(int sa,int sb,int sc){
e1[++en1].b=sb;
e1[en1].v=sc;
e1[en1].next=h[sa];
h[sa]=en1;
}

void AddEdge(int sa,int sb,int sc){
e[++en].b=sb;
e[en].f=sc;
e[en].next=h[sa];
e[en].back=en+1;
h[sa]=en;
swap(sa,sb);
e[++en].b=sb;
e[en].f=0;
e[en].next=h[sa];
e[en].back=en-1;
h[sa]=en;
}

int Spfa(int S,int T){
queue<int> Q;
memset(D,127,sizeof(D));
memset(flag,0,sizeof(flag));
Q.push(S);
D[S]=0;
flag[S]=1;
while(!Q.empty()){
	int u=Q.front();
	Q.pop();
	flag[u]=0;
	for(int i=h[u];i;i=e1[i].next){
		int v=e1[i].b;
		if(D[u]+e1[i].v<D[v]){
			D[v]=D[u]+e1[i].v;
            if(!flag[v]){
				Q.push(v);
				flag[v]=1;
            }
		}
	}
}
return D[T];
}

int Spfa2(int S,int T){
queue<int> Q;
memset(Di,127,sizeof(Di));
memset(flag,0,sizeof(flag));
Q.push(S);
Di[S]=0;
flag[S]=1;
while(!Q.empty()){
	int u=Q.front();
	Q.pop();
	flag[u]=0;
	for(int i=h[u];i;i=e1[i].next){
		int v=e1[i].b;
		if(Di[u]+e1[i].v<Di[v]){
			Di[v]=Di[u]+e1[i].v;
            if(!flag[v]){
				Q.push(v);
				flag[v]=1;
            }
		}
	}
}
return Di[T];
}

int Bfs(){
queue<int> Q;
Q.push(S);
memset(flag,0,sizeof(flag));
flag[S]=1;
while(!Q.empty()){
	int u=Q.front();
	Q.pop();
	for(int i=h[u];i;i=e[i].next){
		int v=e[i].b;
		if(flag[v] || !e[i].f)continue;
		flag[v]=flag[u]+1;
		Q.push(v);
	}
}
return flag[T];
}

int Dfs(int u,int flow){
if(u==T)return flow;
int f=flow;
for(int &i=cur[u];i;i=e[i].next){
	int v=e[i].b,fl;
	if(flag[v]==flag[u]+1 && e[i].f && (fl=Dfs(v,min(f,e[i].f)))){
		f-=fl;
		e[i].f-=fl;
		e[e[i].back].f+=fl;
		if(f==0)return flow;
	}
}
return flow-f;
}

int Dinic(){
int ans=0;
while(Bfs()){
	for(int i=1;i<=n;i++)cur[i]=h[i];
	ans+=Dfs(S,2100000000);
}
return ans;
}

int main(){
freopen("1266.in","r",stdin);
freopen("1266.out","w",stdout);
scanf("%d %d",&n,&m);
for(int i=1;i<=m;i++){
	scanf("%d %d %d %d",&E[i].a,&E[i].b,&E[i].t,&E[i].c);
	AddEdge1(E[i].a,E[i].b,E[i].t);
	AddEdge1(E[i].b,E[i].a,E[i].t);
}
int ans1=Spfa(1,n),ans2=Spfa2(n,1);
memset(h,0,sizeof(h));
printf("%d\n",ans1);
for(int i=1;i<=m;i++){
	if(D[E[i].a]+Di[E[i].b]+E[i].t==ans1){AddEdge(E[i].a,E[i].b,E[i].c);}
	if(Di[E[i].a]+D[E[i].b]+E[i].t==ans1){AddEdge(E[i].b,E[i].a,E[i].c);}
}
S=1;T=n;
ans2=Dinic();
printf("%d\n",ans2);
return 0;
}

这题写了我1.5h……

以后写题目必须认真、仔细！

Pushdown居然写错了……调试了半天

所以以后必须仔细想好细节再写，这样才能节省时间。

#include<cstdio>
#include<algorithm>
using namespace std;

int n,move_to=0;
char s[2000005];

struct Node{
char v;
int rev,siz;
Node *ch[2],*fa;
Node(char ch,Node *fat);
void Pushdown();
void Pushup();
}*root,*Null;

Node::Node(char c,Node *fat=Null){
ch[0]=ch[1]=Null;
fa=fat;
siz=1;
rev=0;
v=c;
}

void Node::Pushdown(){
if(rev){
	rev=0;
	if(ch[0]!=Null)ch[0]->rev^=1;
	if(ch[1]!=Null)ch[1]->rev^=1;
	swap(ch[0]->ch[0],ch[0]->ch[1]);
	swap(ch[1]->ch[0],ch[1]->ch[1]);
}
}

void Node::Pushup(){
siz=1;
if(ch[0]!=Null)siz+=ch[0]->siz;
if(ch[1]!=Null)siz+=ch[1]->siz;
}

void Rotate(Node *x,int kind){
Node *y=x->fa,*z=y->fa;
y->ch[!kind]=x->ch[kind];
if(x->ch[kind]!=Null)x->ch[kind]->fa=y;
x->fa=z;
if(z!=Null)z->ch[z->ch[1]==y]=x;
y->fa=x;
x->ch[kind]=y;
y->Pushup();
x->Pushup();
}

void Splay(Node *x,Node *place){
while(x->fa!=place){
	Node *y=x->fa,*z=y->fa;
	if(z==Null || z==place)Rotate(x,y->ch[0]==x);
	else {
		if(y->ch[1]==x && z->ch[1]==y){Rotate(y,0);Rotate(x,0);}
		else if(y->ch[1]==x && z->ch[0]==y){Rotate(x,0);Rotate(x,1);}
		else if(y->ch[0]==x && z->ch[1]==y){Rotate(x,1);Rotate(x,0);}
		else {Rotate(y,1);Rotate(x,1);}
	}
}
if(place==Null)root=x;
}

Node *Find(Node *splay,int k){
splay->Pushdown();
if(k==splay->ch[0]->siz+1)return splay;
if(k<=splay->ch[0]->siz)return Find(splay->ch[0],k);
return Find(splay->ch[1],k-1-splay->ch[0]->siz);
}

Node *Split(int pos,int tot){
Node *x=Find(root,pos),*y=Find(root,pos+tot+1);
Splay(x,Null);
Splay(y,root);
return y->ch[0];
}

Node *Build(int l,int r){
if(l>r)return Null;
int mid=l+r>>1;
Node *splay=new Node(s[mid],Null);
splay->ch[0]=Build(l,mid-1);
if(splay->ch[0]!=Null)splay->ch[0]->fa=splay;
splay->ch[1]=Build(mid+1,r);
if(splay->ch[1]!=Null)splay->ch[1]->fa=splay;
splay->Pushup();
return splay;
}

void Del_Tree(Node *splay){
if(splay==Null)return;
splay->Pushdown();
Del_Tree(splay->ch[0]);
Del_Tree(splay->ch[1]);
if(splay->ch[0]!=Null)delete splay->ch[0];
if(splay->ch[1]!=Null)delete splay->ch[1];
splay->ch[0]=Null;
splay->ch[1]=Null;
splay->Pushup();
}

Node *GetNull(){
Node *p=new Node('#',Null);
p->ch[0]=p->ch[1]=p->fa=p;
p->siz=p->rev=0;
}

void Build_First(){
Null=GetNull();
s[1]='H';
s[2]='i';
root=Build(1,2);
}

void Insert(int pos,int tot){
Node *x=Find(root,pos+1),*y=Find(root,pos+2);
Splay(x,Null);Splay(y,root);
y->ch[0]=Build(1,tot);
if(y->ch[0]!=Null)y->ch[0]->fa=y;
y->Pushup();
x->Pushup();
}

void Delete(int pos,int tot){
Node *seq=Split(pos,tot),*fat=seq->fa;
Del_Tree(seq);
if(seq!=Null)delete seq;
fat->ch[0]=Null;
fat->Pushup();
fat->fa->Pushup();
}

void Reverse(int pos,int tot){
Node *seq=Split(pos,tot),*fat=seq->fa;
seq->rev^=1;
swap(seq->ch[0],seq->ch[1]);
fat->Pushup();
fat->fa->Pushup();
}

char GetKey(int pos){
Node *u=Split(pos,1);
return u->v;
}

void GetString(int len){
char ch;
while((ch=getchar())=='\n');
s[1]=ch;
for(int i=2;i<=len;i++){s[i]=getchar();}
s[len+1]='\0';
}

int main(){
freopen("1269.in","r",stdin);
freopen("1269.out","w",stdout);
scanf("%d",&n);
Build_First();
for(int i=1;i<=n;i++){
	char opt[10];
	scanf("%s",opt);
	if(opt[0]=='M'){
		int k;
		scanf("%d",&k);
		move_to=k;
	}
	if(opt[0]=='I'){
		int tot;
		scanf("%d",&tot);
		GetString(tot);
		Insert(move_to,tot);
	}
	if(opt[0]=='D'){
		int tot;
		scanf("%d",&tot);
        Delete(move_to+1,tot);
	}
	if(opt[0]=='R'){
		int tot;
		scanf("%d",&tot);
		Reverse(move_to+1,tot);
	}
	if(opt[0]=='G'){
        printf("%c\n",GetKey(move_to+1));
	}
	if(opt[0]=='P')move_to--;
	if(opt[0]=='N')move_to++;
}
return 0;
}

两个都是可持久化线段树，相当于复习一下算法。。

第一个程序我没加路径压缩，第二个加了

第二个读入的操作编号不要异或lastans……在这里卡了一下

#include<cstdio>
#include<algorithm>
using namespace std;

struct SegTree{
int l,r,ls,rs,v;
}tree[2000005];

int root[20005],cnt,deep[200005],n,m;

void Build(int &rt,int l,int r){
if(!rt)rt=++cnt;
if(l==r){tree[rt].v=l;return;}
int mid=l+r>>1;
tree[rt].l=l;
tree[rt].r=r;
Build(tree[rt].ls,l,mid);
Build(tree[rt].rs,mid+1,r);
}

void Change(int x,int &y,int pos,int val){
y=++cnt;
tree[y].l=tree[x].l;
tree[y].r=tree[x].r;
if(tree[x].l==tree[x].r){tree[y].v=val;deep[y]=deep[x];return;}
tree[y].ls=tree[x].ls;
tree[y].rs=tree[x].rs;
int mid=tree[x].l+tree[x].r>>1;
if(pos<=mid)Change(tree[x].ls,tree[y].ls,pos,val);
if(pos>mid)Change(tree[x].rs,tree[y].rs,pos,val);
}

int Query(int rt,int pos){
if(tree[rt].l==tree[rt].r)return rt;
int mid=tree[rt].l+tree[rt].r>>1;
if(pos<=mid)return Query(tree[rt].ls,pos);
if(pos>mid)return Query(tree[rt].rs,pos);
}

void Add(int rt,int pos){
if(tree[rt].l==tree[rt].r){deep[rt]++;return;}
int mid=tree[rt].l+tree[rt].r>>1;
if(pos<=mid)Add(tree[rt].ls,pos);
if(pos>mid)Add(tree[rt].rs,pos);
}

int Find(int rt,int x){
int tp=Query(rt,x);
if(x==tree[tp].v)return tp;
return Find(rt,tree[tp].v);
}

int main(){
freopen("3673.in","r",stdin);
freopen("3673.out","w",stdout);
scanf("%d %d",&n,&m);
Build(root[0],1,n);
for(int i=1;i<=m;i++){
    int opt;
    scanf("%d",&opt);
    if(opt==1){
		int x,y,px,py;
        scanf("%d %d",&x,&y);
        root[i]=root[i-1];
        px=Find(root[i],x);py=Find(root[i],y);
        if(tree[px].v==tree[py].v)continue;
        if(deep[px]>deep[py])swap(px,py);
        Change(root[i-1],root[i],tree[px].v,tree[py].v);
        if(deep[px]==deep[py])Add(root[i],tree[py].v);
    }
    if(opt==2){
		int k;
		scanf("%d",&k);
		root[i]=root[k];
    }
    if(opt==3){
		int x,y;
		root[i]=root[i-1];
		scanf("%d %d",&x,&y);
		if(tree[Find(root[i],x)].v!=tree[Find(root[i],y)].v)puts("0");
		else puts("1");
    }
}
return 0;
}

#include<cstdio>
#include<algorithm>
using namespace std;

int n,m,cnt,lastans=0,deep[10000005],root[200005];

struct SegTree{
int l,r,ls,rs,v;
}tree[10000005];

void Build(int &rt,int l,int r){
if(!rt)rt=++cnt;
tree[rt].l=l;
tree[rt].r=r;
if(l==r){tree[rt].v=l;return;}
int mid=l+r>>1;
Build(tree[rt].ls,l,mid);
Build(tree[rt].rs,mid+1,r);
}

void Change(int x,int &y,int pos,int val){
y=++cnt;
tree[y].l=tree[x].l;
tree[y].r=tree[x].r;
if(tree[x].l==tree[x].r){tree[y].v=val;deep[y]=deep[x];return;}
tree[y].ls=tree[x].ls;
tree[y].rs=tree[x].rs;
int mid=tree[x].l+tree[x].r>>1;
if(pos<=mid)Change(tree[x].ls,tree[y].ls,pos,val);
if(pos>mid)Change(tree[x].rs,tree[y].rs,pos,val);
}

void Add(int rt,int pos){
if(tree[rt].l==tree[rt].r){deep[rt]++;return;}
int mid=tree[rt].l+tree[rt].r>>1;
if(pos<=mid)Add(tree[rt].ls,pos);
if(pos>mid)Add(tree[rt].rs,pos);
}

int Query(int rt,int pos){
if(tree[rt].l==tree[rt].r){return rt;}
int mid=tree[rt].l+tree[rt].r>>1;
if(pos<=mid)return Query(tree[rt].ls,pos);
if(pos>mid)return Query(tree[rt].rs,pos);
}

int Find(int rt,int x){
int p=Query(rt,x);
if(x==tree[p].v){return p;}
int tp=Find(rt,tree[p].v);
Change(rt,rt,tree[p].v,tp);
return tp;
}

int main(){
freopen("3674.in","r",stdin);
freopen("3674.out","w",stdout);
scanf("%d %d",&n,&m);
Build(root[0],1,n);
for(int i=1;i<=m;i++){
    int opt;
    scanf("%d",&opt);
    if(opt==1){
		int x,y,p,q;
		scanf("%d %d",&x,&y);
		x^=lastans;y^=lastans;
        root[i]=root[i-1];
        p=Find(root[i],x);
        q=Find(root[i],y);
        if(tree[p].v==tree[q].v)continue;
        if(deep[p]>deep[q])swap(p,q);
        Change(root[i-1],root[i],tree[p].v,tree[q].v);
        if(deep[p]==deep[q])Add(root[i],tree[q].v);
    }
    if(opt==2){
		int k;
		scanf("%d",&k);
		k^=lastans;
        root[i]=root[k];
    }
    if(opt==3){
		int x,y;
		scanf("%d %d",&x,&y);
		x^=lastans;y^=lastans;
		root[i]=root[i-1];
        if(tree[Find(root[i],x)].v==tree[Find(root[i],y)].v){puts("1");lastans=1;}
        else {puts("0");lastans=0;}
	}
}
return 0;
}

Splay模版题

调试两天总算A啦！

2016/2/21 *1

2016/3/20 *1

#include<cstdio>
#include<algorithm>
using namespace std;

int n,a[1000005],m;

struct Node{
int v,mx,sum,lx,rx,siz,tag,rev;
Node *ch[2],*fa;
Node(int val,Node *fat);
void Pushdown();
void Pushup();
}*root,*Null;

Node::Node(int val=0,Node *fat=Null){
ch[0]=ch[1]=Null;
fa=fat;
v=sum=mx=val;
tag=rev=0;
siz=1;
if(v>=0)lx=rx=v;
else lx=rx=0;
}

void Node::Pushdown(){
if(tag){
	tag=rev=0;
	if(ch[0]!=Null){ch[0]->tag=1;ch[0]->sum=ch[0]->siz*v;ch[0]->v=v;}
	if(ch[1]!=Null){ch[1]->tag=1;ch[1]->sum=ch[1]->siz*v;ch[1]->v=v;}
	if(v>=0){
        if(ch[0]!=Null){ch[0]->lx=ch[0]->mx=ch[0]->rx=v*ch[0]->siz;}
        if(ch[1]!=Null){ch[1]->lx=ch[1]->mx=ch[1]->rx=v*ch[1]->siz;}
	}
	else {
		if(ch[0]!=Null){ch[0]->mx=v;ch[0]->lx=ch[0]->rx=0;}
        if(ch[1]!=Null){ch[1]->mx=v;ch[1]->lx=ch[1]->rx=0;}
	}
}
if(rev){
	rev=0;
	if(ch[0]!=Null)ch[0]->rev^=1;
	if(ch[1]!=Null)ch[1]->rev^=1;
	swap(ch[0]->ch[0],ch[0]->ch[1]);
	swap(ch[1]->ch[0],ch[1]->ch[1]);
	swap(ch[0]->lx,ch[0]->rx);
	swap(ch[1]->lx,ch[1]->rx);
}
}

void Node::Pushup(){
siz=ch[0]->siz+ch[1]->siz+1;
sum=ch[0]->sum+ch[1]->sum+v;
mx=max(ch[0]->mx,ch[1]->mx);
mx=max(mx,ch[0]->rx+v+ch[1]->lx);
lx=max(ch[0]->lx,ch[0]->sum+v+ch[1]->lx);
rx=max(ch[1]->rx,ch[1]->sum+v+ch[0]->rx);
}

void Rotate(Node *x,int kind){
Node *y=x->fa,*z=y->fa;
y->ch[!kind]=x->ch[kind];
if(x->ch[kind]!=Null)x->ch[kind]->fa=y;
x->fa=z;
if(z!=Null)z->ch[z->ch[1]==y]=x;
y->fa=x;
x->ch[kind]=y;
y->Pushup();
x->Pushup();
}

void Splay(Node *x,Node *place){
while(x->fa!=place){
	Node *y=x->fa,*z=y->fa;
	if(z==Null || z==place)Rotate(x,y->ch[0]==x);
	else {
		if(y->ch[0]==x && z->ch[0]==y){Rotate(y,1);Rotate(x,1);}
		else if(y->ch[0]==x && z->ch[1]==y){Rotate(x,1);Rotate(x,0);}
		else if(y->ch[1]==x && z->ch[0]==y){Rotate(x,0);Rotate(x,1);}
		else {Rotate(y,0);Rotate(x,0);}
	}
}
if(place==Null)root=x;
}

Node *Find(Node *splay,int k){
splay->Pushdown();
if(splay->ch[0]->siz+1==k)return splay;
if(splay->ch[0]->siz>=k)return Find(splay->ch[0],k);
return Find(splay->ch[1],k-1-splay->ch[0]->siz);
}

Node *Split(int pos,int tot){
Node *x=Find(root,pos);
Splay(x,Null);
Node *y=Find(root,pos+tot+1);
Splay(y,root);
return y->ch[0];
}

Node *Build(int l,int r){
if(l>r)return Null;
int mid=l+r>>1;
Node *splay=new Node(a[mid],Null);
splay->ch[0]=Build(l,mid-1);
if(splay->ch[0]!=Null)splay->ch[0]->fa=splay;
splay->ch[1]=Build(mid+1,r);
if(splay->ch[1]!=Null)splay->ch[1]->fa=splay;
splay->Pushup();
return splay;
}

void Insert(int pos,int tot){
Node *x=Find(root,pos+1),*y=Find(root,pos+2);
Splay(x,Null);Splay(y,root);
y->ch[0]=Build(1,tot);
if(y->ch[0]!=Null)y->ch[0]->fa=y;
y->Pushup();
x->Pushup();
}

Node *GetNull(){
Node *p=new Node(0,Null);
p->fa=p->ch[0]=p->ch[1]=p;
p->mx=p->v=-1000000000;
p->rev=p->tag=p->siz=p->sum=p->lx=p->rx=0;
return p;
}

void Build_First(){
Null=GetNull();
a[1]=-1000000000;
a[n+2]=-1000000000;
root=Build(1,n+2);
}

void Del_Tree(Node *splay){
if(splay==Null)return;
splay->Pushdown();
Del_Tree(splay->ch[0]);
Del_Tree(splay->ch[1]);
if(splay->ch[0]!=Null)delete splay->ch[0];
if(splay->ch[1]!=Null)delete splay->ch[1];
splay->ch[0]=Null;
splay->ch[1]=Null;
splay->Pushup();
}

void Delete(int pos,int val){
Node *seq=Split(pos,val),*fat=seq->fa;
Del_Tree(seq);
if(seq!=Null)delete seq;
fat->ch[0]=Null;
fat->Pushup();
fat->fa->Pushup();
}

void MakeSame(int pos,int tot,int val){
Node *seq=Split(pos,tot),*fat=seq->fa;
seq->tag=1;
seq->sum=seq->siz*val;
seq->v=val;
if(val>=0)seq->lx=seq->rx=seq->mx=seq->siz*val;
else seq->lx=seq->rx=0,seq->mx=val;
fat->Pushup();
fat->fa->Pushup();
}

void Reverse(int pos,int tot){
Node *seq=Split(pos,tot),*fat=seq->fa;
if(!seq->tag){
	seq->rev^=1;
	swap(seq->ch[0],seq->ch[1]);
	swap(seq->lx,seq->rx);
	fat->Pushup();
	fat->fa->Pushup();
}
}

int GetSum(int pos,int tot){
Node *seq=Split(pos,tot);
return seq->sum;
}

int main(){
freopen("1500.in","r",stdin);
freopen("1500.out","w",stdout);
scanf("%d %d",&n,&m);
for(int i=2;i<=n+1;i++)scanf("%d",&a[i]);
Build_First();
for(int i=1;i<=m;i++){
	char s[10];
    scanf("%s",s);
    if(s[0]=='I'){
		int pos,tot;
		scanf("%d %d",&pos,&tot);
		for(int i=1;i<=tot;i++)scanf("%d",&a[i]);
		Insert(pos,tot);
	}
	if(s[0]=='D'){
		int pos,tot;
		scanf("%d %d",&pos,&tot);
		Delete(pos,tot);
	}
	if(s[0]=='M' && s[2]=='K'){
		int pos,tot,val;
		scanf("%d %d %d",&pos,&tot,&val);
        MakeSame(pos,tot,val);
	}
	if(s[0]=='M' && s[2]=='X'){
		printf("%d\n",root->mx);
	}
	if(s[0]=='R'){
		int pos,tot;
		scanf("%d %d",&pos,&tot);
		Reverse(pos,tot);
	}
	if(s[0]=='G'){
		int pos,tot;
		scanf("%d %d",&pos,&tot);
		printf("%d\n",GetSum(pos,tot));
	}
}
return 0;
}

无语了……

参考hzwer的题解，我自己没想出来……

具体就是先搞一遍LCA，再分三种情况判断

详见hzwer题解：传送门

判定ROOT时居然写了if(ROOT=x)简直爆炸

没救了

#include<cstdio>
#include<algorithm>
using namespace std;
 
int h[100005],en,fa[100005][18],data[100005],dfn,L[100005],R[100005],pre[100005],ROOT=1,bits[20],dep[100005],n,q;
 
struct Edge{
int b,next;
}e[200005];
 
struct SegTree{
int l,r,mn;
}tree[400005];
 
void Pushup(int root){
tree[root].mn=min(tree[root*2].mn,tree[root*2+1].mn);
}
 
void Build(int root,int l,int r){
tree[root].l=l;
tree[root].r=r;
if(l==r){
    tree[root].mn=data[pre[l]];
    return;
}
int mid=l+r>>1;
Build(root*2,l,mid);
Build(root*2+1,mid+1,r);
Pushup(root);
}
 
void Change(int root,int pos,int val){
if(tree[root].l==tree[root].r){
    tree[root].mn=val;
    return;
}
int mid=tree[root].l+tree[root].r>>1;
if(pos<=mid)Change(root*2,pos,val);
if(pos>mid)Change(root*2+1,pos,val);
Pushup(root);
}
 
int GtMn(int root,int l,int r){
if(l>r)return 2100000000;
if(tree[root].l>=l && tree[root].r<=r){
    return tree[root].mn;
}
int mid=tree[root].l+tree[root].r>>1,ans=2100000000;
if(l<=mid)ans=min(ans,GtMn(root*2,l,r));
if(r>mid)ans=min(ans,GtMn(root*2+1,l,r));
return ans;
}
 
void AddEdge(int sa,int sb){
e[++en].b=sb;
e[en].next=h[sa];
h[sa]=en;
}
 
void dfs(int u){
L[u]=++dfn;
pre[dfn]=u;
for(int i=1;i<=18;i++){
    if(bits[i]<=dep[u])fa[u][i]=fa[fa[u][i-1]][i-1];
    else break;
}
for(int i=h[u];i;i=e[i].next){
    int v=e[i].b;
    dep[v]=dep[u]+1;
    fa[v][0]=u;
    dfs(v);
}
R[u]=dfn;
}
 
int main(){
freopen("3306.in","r",stdin);
freopen("3306.out","w",stdout);
bits[0]=1;
for(int i=1;i<=18;i++)bits[i]=bits[i-1]<<1;
scanf("%d %d",&n,&q);
//printf("%d %d\n",n,q);
for(int i=1;i<=n;i++){
    int u;
    scanf("%d %d",&u,&data[i]);
    //printf("%d %d\n",u,data[i]);
    if(u)AddEdge(u,i);
}
dfs(ROOT=1);
Build(1,1,n);
for(int i=1;i<=q;i++){
    char s[5];
    int x,y;
    scanf("%s",s);
    if(s[0]=='V'){
        scanf("%d %d",&x,&y);
        Change(1,L[x],y);
    }
    if(s[0]=='E'){
        scanf("%d",&x);
        ROOT=x;
    }
    if(s[0]=='Q'){
        scanf("%d",&x);
        if(ROOT==x){printf("%d\n",tree[1].mn);continue;}
        if(L[x]<=L[ROOT] && R[x]>=R[ROOT]){
            y=ROOT;
            int deep=dep[y]-dep[x]-1;
            for(int i=0;i<=18;i++){
                if(bits[i]&deep)y=fa[y][i];
            }
            printf("%d\n",min(GtMn(1,1,L[y]-1),GtMn(1,R[y]+1,n)));
            continue;
        }
        printf("%d\n",GtMn(1,L[x],R[x]));
    }
}
return 0;
}

因为一棵树的子树一定在dfs序上是连续的

所以直接修改就行了

#include<cstdio>
#include<algorithm>
using namespace std;

struct Edge{
int b,next;
}e[1000005];

struct SegTree{
int l,r;
long long tag,sum;
}tree[1000005];

int n,q,en,cnt,top[400005],id[400005],pre[400005],dep[400005],son[400005],h[400005],siz[400005],fa[400005];

void AddEdge(int sa,int sb){
e[++en].b=sb;
e[en].next=h[sa];
h[sa]=en;
}

void Pushdown(int root){
if(tree[root].tag){
	tree[root*2].tag+=tree[root].tag;
	tree[root*2].sum+=tree[root].tag*(tree[root*2].r-tree[root*2].l+1);
	tree[root*2+1].tag+=tree[root].tag;
	tree[root*2+1].sum+=tree[root].tag*(tree[root*2+1].r-tree[root*2+1].l+1);
	tree[root].tag=0;
}
}

void Pushup(int root){
tree[root].sum=tree[root*2].sum+tree[root*2+1].sum;
}

void Build(int root,int l,int r){
tree[root].l=l;
tree[root].r=r;
if(l==r){
    tree[root].sum=0;
    return;
}
int mid=(l+r)/2;
Build(root*2,l,mid);
Build(root*2+1,mid+1,r);
tree[root].sum=tree[root*2].sum+tree[root*2+1].sum;
}

void Add(int root,int l,int r,long long v){
if(tree[root].l>=l && tree[root].r<=r){
	tree[root].tag+=v;
	tree[root].sum+=v*(tree[root].r-tree[root].l+1);
	return;
}
Pushdown(root);
int mid=tree[root].l+tree[root].r>>1;
if(l<=mid)Add(root*2,l,r,v);
if(r>mid)Add(root*2+1,l,r,v);
Pushup(root);
}

long long Sum(int root,int l,int r){
if(tree[root].l>=l && tree[root].r<=r){
	return tree[root].sum;
}
Pushdown(root);
int mid=tree[root].l+tree[root].r>>1;
long long ans=0;
if(l<=mid)ans+=Sum(root*2,l,r);
if(r>mid)ans+=Sum(root*2+1,l,r);
return ans;
}

void dfs1(int u,int father,int deep){
fa[u]=father;
dep[u]=deep;
siz[u]=1;
son[u]=0;
for(int i=h[u];i;i=e[i].next){
    int v=e[i].b;
    if(v==father)continue;
    dfs1(v,u,deep+1);
    siz[u]+=siz[v];
    if(siz[v]>siz[son[u]]){
        son[u]=v;
    }
}
}
 
void dfs2(int u,int ux){
top[u]=ux;
id[u]=++cnt;
pre[cnt]=u;
if(son[u])dfs2(son[u],ux);
else return;
for(int i=h[u];i;i=e[i].next){
    int v=e[i].b;
    if(v!=son[u] && v!=fa[u]){dfs2(v,v);}
}
}

void AddLine(int u,int v,long long val){
int f1=top[u],f2=top[v];
while(f1!=f2){
	if(dep[f1]<dep[f2]){swap(u,v);swap(f1,f2);}
	Add(1,id[f1],id[u],val);
	u=fa[f1];
	f1=top[u];
}
if(dep[u]>dep[v])swap(u,v);
//printf("%d %d\n",id[u],id[v]);
Add(1,id[u],id[v],val);
}

int main(){
freopen("2836.in","r",stdin);
freopen("2836.out","w",stdout);
scanf("%d",&n);
for(int i=1;i<n;i++){
	int u,v;
	scanf("%d %d",&u,&v);
	AddEdge(u+1,v+1);
	AddEdge(v+1,u+1);
}
Build(1,1,n);
dfs1(1,0,1);
dfs2(1,1);
scanf("%d",&q);
while(q--){
	int u,v;
	long long val;
	char s[3];
	scanf("%s",s);
	if(s[0]=='A'){
		scanf("%d %d %lld",&u,&v,&val);
		AddLine(u+1,v+1,val);
	}
	if(s[0]=='Q'){
		scanf("%d",&u);
		//printf("IS:%d %d %d\n",id[u+1],siz[u+1],u+1);
		printf("%lld\n",Sum(1,id[u+1],id[u+1]+siz[u+1]-1));
	}
}
return 0;
}

LCT

#include<cstdio>
#include<algorithm>
#include<map>
using namespace std;

int n,m,c,t,have[10005][105];
map<int,int> Mp[1000005];

struct Node{
int rev;
Node *ch[2],*fa;
Node(Node *fat);
void Pushdown();
}*root[1000005],*Null;

Node::Node(Node *fat=Null){
ch[0]=ch[1]=Null;
fa=fat;
rev=0;
}

Node *GetNull(){
Node *re=new Node(re);
re->rev=0;
re->ch[0]=re->fa=re->ch[1]=re;
return re;
}

void Node::Pushdown(){
if(rev){
	if(ch[0]!=Null)ch[0]->rev^=1;
	if(ch[1]!=Null)ch[1]->rev^=1;
	swap(ch[0],ch[1]);
	rev=0;
}
}

int Notroot(Node *x){
return (x->fa->ch[0]==x)||(x->fa->ch[1]==x);
}

void Prepare(Node *x){
if(Notroot(x))Prepare(x->fa);
x->Pushdown();
}

void Rotate(Node *x,int kind){
Node *y=x->fa,*z=y->fa;
y->ch[!kind]=x->ch[kind];
if(x->ch[kind]!=Null)x->ch[kind]->fa=y;
x->fa=z;
if(Notroot(y))z->ch[z->ch[1]==y]=x;
y->fa=x;
x->ch[kind]=y;
}

void Splay(Node *x){
Prepare(x);
while(Notroot(x)){
	Node *y=x->fa,*z=y->fa;
	if(!Notroot(y))Rotate(x,y->ch[0]==x);
	else {
		if(y->ch[0]==x && z->ch[0]==y){Rotate(y,1);Rotate(x,1);}
		else if(y->ch[0]==x && z->ch[1]==y){Rotate(x,1);Rotate(x,0);}
		else if(y->ch[1]==x && z->ch[0]==y){Rotate(x,0);Rotate(x,1);}
		else {Rotate(y,0);Rotate(x,0);}
	}
}
}

void Access(Node *x){
for(Node *y=Null;x!=Null;y=x,x=x->fa){Splay(x);x->ch[1]=y;}
}

void Makeroot(Node *x){
Access(x);
Splay(x);
x->rev^=1;
}

void Link(Node *u,Node *v){
Makeroot(u);
u->fa=v;
}

void Cut(Node *u,Node *v){
Makeroot(u);
Access(v);
Splay(v);
if(v->ch[0]==u){v->ch[0]=Null;u->fa=Null;}
}

Node *Find(Node *x){
Access(x);
Splay(x);
while(x->ch[0]!=Null)x=x->ch[0];
return x;
}

int GetPoint(int x,int y){
return x+(y-1)*n;
}

Node *ToLct(int x,int c){
return root[GetPoint(x,c)];
}

void Change(int x,int y,int z){
int Tok=Mp[x][y];
if(Tok==0){puts("No such cable.");return;}
if(Tok==z){puts("Already owned.");return;}
//printf("%d %d\n",have[x][z],have[y][z]);
if(have[x][z]==2 || have[y][z]==2){puts("Forbidden: monopoly.");return;}
Node *u1=ToLct(x,Tok),*u2=ToLct(x,z),*v1=ToLct(y,Tok),*v2=ToLct(y,z);
//printf("%d %d\n",Find(u2),Find(v2));
if(Find(u2)==Find(v2)){puts("Forbidden: redundant.");return;}
Cut(u1,v1);
have[x][Tok]--;
have[y][Tok]--;
have[x][z]++;
have[y][z]++;
Mp[x][y]=z;
Link(u2,v2);
puts("Sold.");
}

int main(){
freopen("3651.in","r",stdin);
freopen("3651.out","w",stdout);
scanf("%d %d %d %d",&n,&m,&c,&t);
Null=GetNull();
for(int i=1;i<=n*c;i++){root[i]=new Node(Null);}
//printf("%d %d %d %d\n",Null,Null->ch[0],Null->ch[1],Null->fa);
for(int i=1;i<=m;i++){
	int s1,s2,k;
	scanf("%d %d %d",&s1,&s2,&k);
	if(s1>s2)swap(s1,s2);
	have[s1][k]++;
	have[s2][k]++;
	Mp[s1][s2]=k;
	//printf("%d %d %d | %d %d N*C:%d\n",s1,s2,k,GetPoint(s1,k),GetPoint(s2,k),n*c);
	Node *x=ToLct(s1,k),*y=ToLct(s2,k);
	Link(x,y);
}
for(int i=1;i<=t;i++){
	int s1,s2,k;
	scanf("%d %d %d",&s1,&s2,&k);
	if(s1>s2)swap(s1,s2);
    Change(s1,s2,k);
}
return 0;
}

LCT直接上

记录子树的大小

#include<cstdio>
#include<algorithm>
using namespace std;

int n,m,Next[200005];

struct Node{
int siz,rev;
Node *ch[2],*fa;
Node(Node *fat);
void Pushup();
void Pushdown();
}*root[200005],*Null;

Node::Node(Node *fat){
ch[0]=ch[1]=Null;
fa=fat;
siz=1;
rev=0;
}

void Node::Pushup(){
siz=1;
if(ch[0]!=Null)siz+=ch[0]->siz;
if(ch[1]!=Null)siz+=ch[1]->siz;
}

void Node::Pushdown(){
if(rev){
	if(ch[0]!=Null)ch[0]->rev^=1;
	if(ch[1]!=Null)ch[1]->rev^=1;
	swap(ch[0],ch[1]);
	rev=0;
}
}

int Notroot(Node *x){
return (x->fa->ch[0]==x)||(x->fa->ch[1]==x);
}

void Prepare(Node *x){
if(Notroot(x))Prepare(x->fa);
x->Pushdown();
}

void Rotate(Node *x,int kind){
Node *y=x->fa,*z=y->fa;
y->ch[!kind]=x->ch[kind];
if(x->ch[kind]!=Null)x->ch[kind]->fa=y;
x->fa=z;
if(Notroot(y))z->ch[z->ch[1]==y]=x;
y->fa=x;
x->ch[kind]=y;
y->Pushup();
x->Pushup();
}

void Splay(Node *x){
Prepare(x);
while(Notroot(x)){
	Node *y=x->fa,*z=y->fa;
	if(!Notroot(y)){Rotate(x,y->ch[0]==x);}
	else {
		if(y->ch[1]==x && z->ch[1]==y){Rotate(y,0);Rotate(x,0);}
		else if(y->ch[1]==x && z->ch[0]==y){Rotate(x,0);Rotate(x,1);}
		else if(y->ch[0]==x && z->ch[0]==y){Rotate(y,1);Rotate(x,1);}
		else {Rotate(x,1);Rotate(x,0);}
	}
}
}

void Access(Node *x){
for(Node *y=Null;x!=Null;y=x,x=x->fa){Splay(x);x->ch[1]=y;x->Pushup();}
}

void Makeroot(Node *x){
Access(x);
Splay(x);
x->rev^=1;
}

void Link(Node *x,Node *y){
Makeroot(x);
x->fa=y;
}

void Cut(Node *x,Node *y){
Makeroot(x);
Access(y);
Splay(y);
if(y->ch[0]==x){y->ch[0]=Null;x->fa=Null;}
}

Node *Find(Node *x){
Access(x);
Splay(x);
while(x->ch[0]!=Null)x=x->ch[0];
return x;
}

Node *ToLct(int x){
return root[x];
}

Node *GetNull(){
Node *u=new Node(Null);
u->fa=u->ch[0]=u->ch[1]=u;
u->siz=0;
u->rev=0;
return u;
}

int Jump(int x){
Node *u=ToLct(x);
Makeroot(ToLct(n+1));
Access(u);
Splay(u);
return u->ch[0]->siz;
}

void Change(int x,int y){
//Node *u=ToLct(x),*v=ToLct(Next[x]);
//printf("Tp%d\n",Next[x]);
int t=min(x+y,n+1);
//printf("Tpt%d\n",t);
Cut(ToLct(x),ToLct(Next[x]));
Link(ToLct(x),ToLct(t));
Next[x]=t;
}

int main(){
freopen("2002.in","r",stdin);
freopen("2002.out","w",stdout);
Null=GetNull();
scanf("%d",&n);
root[n+1]=new Node(Null);
for(int i=1;i<=n;i++){
	int tp;
	scanf("%d",&tp);
	root[i]=new Node(Null);
	Next[i]=min(n+1,tp+i);
}
for(int i=1;i<=n;i++){
	Link(ToLct(i),ToLct(Next[i]));
}
scanf("%d",&m);
for(int i=1;i<=m;i++){
	int opt,x,y;
	scanf("%d",&opt);
	if(opt==1){scanf("%d",&x);printf("%d\n",Jump(x+1));}
	if(opt==2){scanf("%d %d",&x,&y);Change(x+1,y);}
}
return 0;
}