Bzoj 3784: path on the tree

Description

Ask a tree forward \ (k\) The large path of the Benquan.

Sol

Divide and conquer the side.

Thank you very much for the data no Daisy diagram.

In order to write the side of the division to try and then opened the problem.

Edge Division is very good to think, choose a heavy edge, divided into two parts, and then to find the maximum value, each heavy edge of a heap maintenance, the global heap saved the answer.

Rebuild seems to write a problem ah qwq ... Crazy re more than ... In the end, no tree can be rebuilt directly.

Rebuild I just want to make him into a two-fork tree, each point of the degree of not more than 3 or 4 is almost enough.

Code

/************************************************************** problem:3784 User:beiyu language:c++ Result : Accepted time:4540 ms memory:26660 kb****************************************************************/#include &L T;bits/stdc++.h>using namespace Std; #define DEBUG (a) cout<< #a << "=" <<a<< "" #define MPR make_pairtypedef pair< int,int > PR; typedef pair< INT,PR > Prr;const int N = 100500; int N,k,rt,rtt;int D[n],sz[n],ud[n];int vis[n<<1]; int cnte;struct Edge {int to,w;} edge[n<<2];vector< int > G[n];p riority_queue< PR > qq;priority_queue< PR > q[n];vector< int &G T nxt[n];vector< int > Tmp[n][2];    inline int in (int x=0,char Ch=getchar ()) {while (ch> ' 9 ' | | ch< ' 0 ') Ch=getchar (); while (ch>= ' 0 ' && ch<= ' 9 ') x=x*10+ch-' 0 ', Ch=getchar (); return x; } void Addedge (int fr,int to,int W) {g[fr].push_back (cnte); edge[cnte++]= (Edge) {to,w};} void Print () {cout<< " StaRT "<<endl;        for (int i=1;i<=n;i++) {cout<<i<< "--"; for (int j=0;j< (int) g[i].size (); j + +) cout<< "ID:" <<g[i][j]<< "" <<edge[g[i][j]].to<        < "";    cout<<endl; } cout<< "-------------------------" &LT;&LT;ENDL;}    void ReBuild (int u,int fa) {int cnt=0,id=-1,lst=0,fst=0; if (G[u].size () >3) for (int i=g[u].size () -1,v;i>=1;i--) if ((v=edge[g[u][i]].to)!=FA) {if (cnt&1            ) {G[n].push_back (g[u][i]);                }else {g[++n].push_back (g[u][i]);                    if (LST) {Addedge (lst,n,0);                Addedge (n,lst,0);                }else {fst=n;            }lst=n;            } cnt^=1;            Edge[g[u][i]^1].to=n;        G[u].pop_back ();    }else Id=g[u][i],g[u].pop_back ();    if (id!=-1) g[u].push_back (ID);    if (FST) Addedge (u,fst,0), Addedge (fst,u,0); for (int i=0;i< (int) g[U].size (); i++) if (EDGE[G[U][I]].TO!=FA) ReBuild (edge[g[u][i]].to,u);    } void GetSize (int u,int fa) {d[u]=d[fa]+1,sz[u]=1; for (int i=g[u].size () -1,v;~i;i--) if ((v=edge[g[u][i]].to)!=fa &&!vis[g[u][i]]) {getsize (v,u), Sz[u]+=sz[v]    ; }}void getroot (int u,int nn) {rt=-1,rtt=n; GetSize (u,u);//for (int i=1;i<=n;i++) cout<<sz[i]<< "", cout<<endl;//for (int i=1;i<=n;i++)    cout<<d[i]<< "";cout<<endl;    queue< PR > Q;q.push (MPR (u,u)); for (PR x;! Q.empty ();)        {X=q.front (), Q.pop ();        int u=x.first,tmp; for (int i=0,v;i< (int) g[u].size (); i++) if ((v=edge[g[u][i]].to)!=x.second &&!vis[g[u][i]]) {if (D[U]&G            T;D[V]) Tmp=max (Sz[u],nn-sz[u]);            else Tmp=max (Sz[v],nn-sz[v]);//debug (U), Debug (v), Debug (TMP), Debug (g[u][i)) <<endl;            if (Tmp<rtt) rtt=tmp,rt=g[u][i];        Q.push (MPR (v,u)); }}//Debug (U), debug (RT) <<endl;} void Getdep (inT u,int fa,int w,vector< int > &vv) {vv.push_back (w); for (int i=0,v;i< (int) g[u].size (); i++) if ((v=edge[g[u][i]].to)!=fa &&!vis[g[u][i]) {GETDEP (v,u,w+edge[    G[U][I]].W,VV);    }} void Getans (int x,int nn) {vis[x]=vis[x^1]=1;    int u=edge[x].to,v=edge[x^1].to;         GETDEP (U,u,0,tmp[x][0]), GETDEP (v,v,0,tmp[x][1]);    Sort (Tmp[x][0].begin (), tmp[x][0].end (),greater< int > ());     Sort (Tmp[x][1].begin (), tmp[x][1].end (),greater< int > ()); cout<< "---------------------" <<endl;//debug (x), debug (NN), Debug (U), Debug (v) <<endl;//for (int i=0;i< (int) tmp[x][0].size (); i++) cout<<tmp[x][0][i]<< ""; cout<<endl;//for (int i=0;i< (int)          Tmp[x][1].size (); i++) cout<<tmp[x][1][i]<< "";cout<<endl;    Nxt[x].resize (Tmp[x][0].size ());         for (int i=0;i< (int) tmp[x][0].size (); i++) nxt[x][i]=0; for (int i=0;i< (int) tmp[x][0].size (); i++) Q[x].push (MPR (tmp[x][0][i]+tmp[x][1][0]+edGe[x].w,i));    Debug (TMP[X][0][I]+TMP[X][1][0]+EDGE[X].W)//debug (Q[x].top (). First) <<endl;         Qq.push (MPR (Q[x].top (). first,x));    if (D[u]<d[v]) swap (U,V);    int Ss=sz[u];    Getroot (U,SS);    if (rt!=-1) Getans (RT,SS);    Getroot (V,NN-SS); if (rt!=-1) Getans (RT,NN-SS);}    void Init () {n=in (), K=in ();     for (int i=1,u,v,w;i<n;i++) u=in (), V=in (), W=in (), Addedge (u,v,w), Addedge (V,U,W);     ReBuild (a);     Print ();         cout<< "Qwq" <<endl;     Getroot (1,n);         Debug (RT) <<endl;     Getans (Rt,n);    }void Del (int x) {PR r=q[x].top ();    Q[x].pop ();    int U=r.second; if (nxt[x][u]+1< (int) tmp[x][1].size ()) Nxt[x][u]++,q[x].push (MPR (TMP[X][0][U]+TMP[X][1][NXT[X][U]]+EDGE[X].W,    u)); Qq.push (MPR (Q[x].top (). first,x));}    int Query () {PR x=qq.top (); Qq.pop ();    int R=x.first,u=x.second;         Del (U); return r;}    int main () {//Freopen ("In.in", "R", stdin);//Ios::sync_with_stdio (FALSE);         Init (); FoR (; k--;)    {printf ("%d\n", Query ()); } return 0;}

　　

Bzoj 3784: path on the tree