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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#692655 | #5439. Meet in the Middle | jinqihao2023 | TL | 0ms | 0kb | C++14 | 4.7kb | 2024-10-31 14:52:32 | 2024-10-31 14:52:32 |
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=2e5+5,M=5e5+5;
ll ans[M],d2[N],d1[N];
int val1[N];
int n,tot,T,num,sz[N],a[M],b[M],q,fa[N];
struct abc{int to,v,p;};
vector<abc>son1[N],son2[N],son[N];
bool vis[N];
int dfn[N],d[N],sign,fp[N];
vector<pair<int,int> >que[N];
int minn[19][N];
void dfs2(int x,int prt)
{
sign++,dfn[x]=sign,fp[sign]=x;
for(auto y:son2[x])if(y.to!=prt)fa[y.to]=x,d[y.to]=d[x]+1,d2[y.to]=d2[x]+y.v,dfs2(y.to,x);
}
int ask(int l,int r)
{
int k=__lg(r-l+1);
if(d[minn[k][l]]<d[minn[k][r-(1<<k)+1]])return minn[k][l];
return minn[k][r-(1<<k)+1];
}
int lca(int x,int y)
{
if(x==y)return x;if(dfn[x]>dfn[y])swap(x,y);
return fa[ask(dfn[x]+1,dfn[y])];
}
ll gdis(int x,int y){return d2[x]+d2[y]-2*d2[lca(x,y)];}
void rebuild(int x,int prt)
{
int st=tot;
if(son1[x].size()>3)
{
for(auto y:son1[x])if(y.to!=prt)
{
tot++;
if(tot>st+1)num++,son[tot-1].push_back((abc){tot,0,num}),son[tot].push_back((abc){tot-1,0,num}),val1[num]=0;
else num++,son[x].push_back((abc){tot,0,num}),son[tot].push_back((abc){x,0,num}),val1[num]=0;
num++,son[tot].push_back((abc){y.to,y.v,num}),son[y.to].push_back((abc){tot,y.v,num}),val1[num]=y.v;
}
}
else for(auto y:son1[x])if(y.to!=prt)num++,son[x].push_back((abc){y.to,y.v,num}),son[y.to].push_back((abc){x,y.v,num}),val1[num]=y.v;
for(auto y:son1[x])if(y.to!=prt)rebuild(y.to,x);
}
int nowv,rtu,rtv,rtp,fa1[N],fv1[N];
void pre(int x,int prt)
{
nowv++;
for(auto y:son[x])if(y.to!=prt && !vis[y.p])fa1[y.to]=x,fv1[y.to]=y.p,pre(y.to,x);
}
void get_rt(int x,int prt)
{
sz[x]=1;
for(auto y:son[x])if(y.to!=prt && !vis[y.p])get_rt(y.to,x),sz[x]+=sz[y.to];
if(!rtu || max(sz[x],nowv-sz[x])<max(sz[rtu],nowv-sz[rtu]))rtu=x,rtv=fa1[x],rtp=fv1[x];
}
vector<int>ver,query;
void dfs1(int x,int prt)
{
if(x<=n)ver.push_back(x);
for(auto y:son[x])if(y.to!=prt && !vis[y.p])dfs1(y.to,x);
}
void dfs0(int x,int prt)
{
for(auto y:son[x])if(y.to!=prt && !vis[y.p])d1[y.to]=d1[x]+y.v,dfs0(y.to,x);
}
void get_que(int x,int prt)
{
for(auto i:que[x])query.push_back(i.second);
for(auto y:son[x])if(y.to!=prt && !vis[y.p])get_que(y.to,x);
}
void slv()
{
if(!ver.size() || !query.size())return ;
int u=ver[0],v=ver[0],len=ver.size();
ll nd=2*d1[u];
for(int i=1;i<len;i++)
{
ll nd1=gdis(u,ver[i])+d1[ver[i]]+d1[u],nd2=gdis(v,ver[i])+d1[ver[i]]+d1[v];
if(nd1>nd2)
{
if(nd1>nd)v=ver[i],nd=nd1;
}
else if(nd2>nd)u=ver[i],nd=nd2;
}
for(auto i:query)
{
ans[i]=max(ans[i],max(gdis(b[i],u)+d1[u]+d1[a[i]],gdis(b[i],v)+d1[v]+d1[a[i]]));
}
}
void solve(int u,int v,int p)
{
vis[p]=1;
d1[u]=val1[p],d1[v]=0,dfs0(u,v),dfs0(v,u);
ver.clear(),query.clear(),dfs1(u,v),get_que(v,u),slv();
ver.clear(),query.clear(),dfs1(v,u),get_que(u,v),slv();
nowv=0,rtu=0,rtv=0,rtp=0,pre(u,v),get_rt(u,v);if(nowv>1)solve(rtu,rtv,rtp);
nowv=0,rtu=0,rtv=0,rtp=0,pre(v,u),get_rt(v,u);if(nowv>1)solve(rtu,rtv,rtp);
}
namespace IO {
const int SIZE=(1<<21)+1;
char ibuf[SIZE],*iS,*iT,obuf[SIZE],*oS=obuf,*oT=oS+SIZE-1,c,qu[55];int f, qr;
#define gc() (iS==iT?(iT=(iS=ibuf)+fread(ibuf,1,SIZE,stdin),(iS==iT?EOF:*iS++)):*iS++)
inline void flush(){fwrite(obuf,1,oS-obuf,stdout),oS=obuf;}
inline void putc(char x){*oS++=x;if(oS==oT)flush();}
template <class I>
inline void read(I &x){
for(f=1,c=gc();c<'0'||c>'9';c=gc())if(c=='-')f=-1;
for(x=0;c<='9'&&c>='0';c=gc())x=x*10+(c&15);x*=f;
}
template <class I>
inline void print(I x){
if(!x)putc('0');if(x<0)putc('-'),x=-x;
while(x)qu[++qr]=x%10+'0',x/=10;
while(qr)putc(qu[qr --]);
}
struct Flusher_ {~Flusher_(){flush();}}io_flusher_;
}
using IO::read;
using IO::putc;
using IO::print;
void solve()
{
read(n),tot=n,num=0,sign=0;
for(int i=1,x,y,z;i<n;i++)read(x),read(y),read(z),son1[x].push_back((abc){y,z,0}),son1[y].push_back({x,z,0});
for(int i=1,x,y,z;i<n;i++)read(x),read(y),read(z),son2[x].push_back((abc){y,z,0}),son2[y].push_back({x,z,0});
read(q);
for(int i=1,x,y;i<=q;i++)read(x),read(y),que[x].push_back({y,i}),a[i]=x,b[i]=y;
dfs2(1,0);
for(int i=1;i<=n;i++)minn[0][i]=fp[i];
for(int i=1;(1<<i)<=n;i++)for(int j=1;j+(1<<i)-1<=n;j++)
{
if(d[minn[i-1][j]]<d[minn[i-1][j+(1<<i-1)]])minn[i][j]=minn[i-1][j];
else minn[i][j]=minn[i-1][j+(1<<i-1)];
}
rebuild(1,0);
fa1[1]=0,fv1[1]=0,nowv=0,rtu=0,rtv=0,rtp=0,pre(1,0),get_rt(1,0);
solve(rtu,rtv,rtp);
for(int i=1;i<=q;i++)print(ans[i]),putc('\n');
for(int i=1;i<=q;i++)ans[i]=0;
for(int i=1;i<=n;i++)son1[i].clear(),son2[i].clear(),que[i].clear();
for(int i=1;i<=tot;i++)son[i].clear();
for(int i=1;i<=num;i++)vis[i]=0;
}
int main()
{
read(T);
while(T--)solve();
return 0;
}
Details
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Test #1:
score: 0
Time Limit Exceeded
input:
3 4 1 2 1 2 3 2 1 2 2 2 3 1 1 1 1 2 2 1 2 2