P2016 战略游戏(dp)

https://www.luogu.com.cn/problem/P2016

思路：类似上司的舞会

#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e3+100;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
vector<LL>g[maxn];
LL dp[maxn][2];
void dfs(LL u,LL fa){
     dp[u][1]=1;
     dp[u][0]=0;
     for(LL i=0;i<g[u].size();i++){
         LL v=g[u][i];
         if(v==fa) continue;
         dfs(v,u);
         dp[u][1]+=min(dp[v][0],dp[v][1]);
         dp[u][0]+=dp[v][1];
     }
}
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL n;cin>>n;
   for(LL i=1;i<=n;i++){
       LL id;cin>>id;
       id++;
       LL m;cin>>m;
       for(LL j=1;j<=m;j++){
           LL v;cin>>v;v++;
           g[id].push_back(v);
           g[v].push_back(id);
       }
   }
   dfs(1,0);
   cout<<min(dp[1][1],dp[1][0])<<"\n";
   return 0;
}