UVA1218，POJ3398 完美服务器（树形DP）

代码来自blog

#include<cstdio>#include<algorithm>#include<vector>#include<queue>#include<cstring>using namespace std;const int maxn=10010;vector<int> g[maxn];int d[maxn][3];int vis[maxn];int dp(int u){    vis[u]=1;    d[u][0]=1,d[u][1]=0,d[u][2]=maxn;    queue<int> q;    for(int i=0;i<g[u].size();++i)        if(!vis[g[u][i]]){            dp(g[u][i]);            q.push(g[u][i]);            d[u][0]+=min(d[g[u][i]][0],d[g[u][i]][1]);            d[u][1]+=d[g[u][i]][2];        }    while(!q.empty()){        d[u][2]=min(d[u][2],d[u][1]-d[q.front()][2]+d[q.front()][0]);        q.pop();    }    return 0;}int main(){    int n;    while(~scanf("%d",&n)&&n!=-1){        if(!n) continue;        for(int i=1;i<=n;++i) g[i].clear();        memset(vis,0,sizeof(vis));        for(int i=1;i<n;++i){            int u,v;scanf("%d%d",&u,&v);            g[u].push_back(v);            g[v].push_back(u);        }        dp(1);        printf("%d\n",min(d[1][0],d[1][2]));    }    return 0;}