HDU 4276 the Ghost Blows light (tree shape)

Test instructions: Give a tree of n nodes, start 1, end N, the connected two nodes have a distance, each node has a value, give a time t. Q What is the maximum value achieved from 1 to N in a given time t?

Idea: first from 1 to N, if the total time is not enough to go, directly exit, otherwise the time deducted, these edge right set to 0, and then do the tree-shaped DP

1#include <algorithm>2#include <cstdio>3#include <cmath>4#include <cstring>5#include <iostream>6 intn,m;7 inttot,go[200005],first[200005],next[200005],val[200005];8 intc[200005],vis[200005],pre[200005],edge[200005],op[200005];9 intf[505][505],v[200005];Ten intRead () { One     intt=0, f=1;CharCh=GetChar (); A      while(ch<'0'|| Ch>'9'){if(ch=='-') f=-1; ch=GetChar ();} -      while('0'<=ch&&ch<='9') {t=t*Ten+ch-'0'; ch=GetChar ();} -     returnt*F; the } - voidInsertintXintYintz) { -tot++; -go[tot]=y; +next[tot]=First[x]; -first[x]=tot; +val[tot]=Z; A } at voidAddintXintYintz) { -Insert (x, y, z); op[tot]=tot+1; -Insert (y,x,z); op[tot]=tot-1; - } - voidBFs () { -      for(intI=1; i<=n;i++) vis[i]=pre[i]=edge[i]=0; in     intH=0, t=1; -c[1]=1; vis[1]=1; to      while(h<=t) { +h++; -          for(intI=first[c[h]];i;i=Next[i]) { the             intPur=Go[i]; *             if(Vis[pur])Continue; $pre[pur]=C[h];Panax Notoginsengedge[pur]=i; -c[++t]=pur; thevis[pur]=1; +         } A     } the } + voidprework () { -      for(inti=n;i!=1; i=Pre[i]) { $m-=Val[edge[i]]; $val[edge[i]]=val[op[edge[i]]]=0; -     } - } the voidDfsintXintFA) { -      for(intI=0; i<=m;i++) f[x][i]=0;Wuyi      for(intI=first[x];i;i=Next[i]) { the         intPur=Go[i]; -         if(PUR==FA)Continue; Wu DFS (pur,x); -         intdis=Val[i]; Aboutdis*=2; $          for(intk=m;k>=dis;k--) -           for(intj=0; j+dis<=k;j++) -F[x][k]=std::max (f[x][k],f[pur][j]+f[x][k-j-dis]); -     } A      for(intI=0; i<=m;i++) +f[x][i]+=V[x]; the } - intMain () { $      while(SCANF ("%d%d", &n,&m)! =EOF) { the      if(n==0&&m==0)return 0; thetot=0; the       for(intI=1; i<=n;i++) first[i]=0; the       for(intI=1; i<n;i++){ -          intx, y, z inX=read (); Y=read (); z=read (); the Add (x, y, z); the      } About       for(intI=1; i<=n;i++) v[i]=read (); the BFS (); the prework (); the      if(m<0){ +printf"Human beings die in pursuit of wealth, and birds die in pursuit of food!\n"); -         Continue; the      }BayiDfs1,0); theprintf"%d\n", f[1][m]); the     } -     return 0; -}

HDU 4276 the Ghost Blows light (tree shape)