Hdu 1520 Anniversary party (树形dp入门，类似最大独立集)

来源：互联网发布：数据库中column 编辑：程序博客网时间：2024/05/21 11:58

#include <cstdio>#include <vector>#include <cstring>#include <iostream>#include <algorithm>using namespace std;const int maxn = 6100;vector<int> G[maxn];int d[maxn][2],c[maxn];/*1 该节点已经选取0 该节点未选区*/bool vis[maxn][2];int dp(int i,int j,int f){   if(vis[i][j]) return d[i][j];   vis[i][j] =true;   if(G[i].size()==1&&G[i][0]==f){       return d[i][j] = 0;   }   d[i][j]=0;   for(int k=0;k<G[i].size();k++){      if(G[i][k]==f) continue;      if(j&1) d[i][j]+=dp(G[i][k],0,i);      else    d[i][j]+=max(dp(G[i][k],0,i),dp(G[i][k],1,i)+c[G[i][k]]);   }   return d[i][j];}int main(){    int n;         while(scanf("%d",&n)==1){          for(int i=1;i<=n;i++){              G[i].clear();              scanf("%d",&c[i]);          }          for(int i=1;i<=n;i++){              int x,y;              scanf("%d %d",&x,&y);              if(!x||!y) break;              G[x].push_back(y);              G[y].push_back(x);          }          memset(vis,false,sizeof(vis));          printf("%d\n",max(dp(1,0,-1),dp(1,1,-1)+c[1]));         }    return 0;}

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