[poj3417] Network (lca+ tree DP)

Test instructions: Give a tree without a root, and then give the M edge below, the m edge connected, each time you go to two sides, a rule is a tree edge, a new side, ask how many kinds of programs can make the tree break.

The key to solve the problem: the edge of the right to the point of power, record each side by the ring coverage of the number of times, through Val[a]++,val[b]++,val[lca (A, B)]-=2, to control each point above the edge, so the tree vertices to be removed.

A long time No 1 A, happy

1 //#pragma COMMENT (linker, "/stack:1024000000,1024000000")2#include <cstdio>3#include <cstring>4#include <algorithm>5#include <cstdlib>6#include <cmath>7#include <iostream>8#include <vector>9typedefLong Longll;Ten using namespacestd;  One Const intmaxn=101000;  A Const intmaxm= -;  - int_pow[maxm],m,n;  - intHead[maxn],tot; the intver[maxn*2],depth[maxn*2],first[maxn],rmq[maxn*2][ -],id;//5 arrays, note which one needs to multiply by 2 - intPRE[MAXN],VAL[MAXN]; - intans; -InlineintRead () { +     Chark=0;CharLs;ls=getchar (); for(;ls<'0'|| Ls>'9'; k=ls,ls=GetChar ()); -     intx=0; for(; ls>='0'&&ls<='9'; Ls=getchar ()) x= (x<<3) + (x<<1) +ls-'0'; +     if(k=='-') x=0-X;returnx; A } at  - structedge{ -     intto,nxt;  -}e[maxn*2];//chain-forward star achievement -  - voidinit () { inmemset (head,-1,sizeofhead);  -tot=0; toId=0; +ans=0; - } the  * voidAdd_edge (intUintv) {   $e[tot].to=v;Panax Notoginsenge[tot].nxt=Head[u]; -head[u]=tot++; the } +    A voidDfsintUintFaintDEP) { theVer[++id]=u;//number of nodes visited by the first I +DEPTH[ID]=DEP;//the node depth to which I visited -first[u]=ID; $      for(inti=head[u];i!=-1; i=e[i].nxt) { $         intv=e[i].to; -         if(V==FA)Continue; -         //Pre[v]=u; theDFS (v,u,dep+1); -Ver[++id]=u;//Post -Traversal, revisit the parent nodeWuyidepth[id]=DEP; the     } - } Wu  - voidRmq_init (intN) { About     intk=int(log (n)/log (2)); $      for(intI=1; i<=n;++i) rmq[i][0]=i;  -      for(intj=1; j<=k;++j) {   -          for(intI=1; i+_pow[j]-1<=n;++i) {//because the index is stored -             inta=rmq[i][j-1],b=rmq[i+_pow[j-1]][j-1];  ARMQ[I][J]=DEPTH[A]&LT;DEPTH[B]?a:b; +         } the     } - } $    the intRmq_query (intLintR) { the     intk=int(Log (r-l+1.0)/log (2.0));  the     inta=rmq[l][k],b=rmq[r-_pow[k]+1][k];  the     returnDEPTH[A]&LT;DEPTH[B]?a:b; -}//The returned index is still in    the intLCA (intUintv) { the     intx=first[u],y=First[v];  About     if(x>y) Swap (x, y);  the     intres=rmq_query (x, y);  the     returnVer[res]; the } + voidDfsintUintFA) { -      for(inti=head[u];i!=-1; i=e[i].nxt) { the         intv=e[i].to;Bayi         if(V==FA)Continue; the DFS (v,u); theval[u]+=Val[v]; -     } -     if(val[u]==1) ans++; the     Else if(!val[u]&&u!=1) ans+=m; the } the  the intMain () { -      for(intI=0; i<maxm;++i) _pow[i]=1<<i;//pretreatment 2^n the     intk,a,b; theN=read (); m=read (); the init ();94     //for (int i=1;i<=n;i++) val[i]=read (); the      for(intI=0; i<n-1;++i) { theA=read (), b=read (); the Add_edge (A, b);98 Add_edge (b,a); About     } -Dfs1,-1,0);101Rmq_init (2*n-1);102      for(intI=0; i<m;++i) {103A=read (); b=read ();104Val[a]++,val[b]++,val[lca (A, b)]-=2; the     }106Dfs1,-1);107printf"%d\n", ans);108     109     return 0; the}

[poj3417] Network (lca+ tree DP)