bzoj4349: 最小树形图&&bzoj2260: 商店购物

双倍经验大法吼

昨天发现不会最小属性图&朱刘算法啊

吓得我赶紧补了一发

朱刘算法模板题

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#include <iostream> #include <cstdio> #include <cmath> #include <cstring> #include <cstdlib> #include <algorithm> #define N 55 #define M 2505   using namespace std; struct edge{     int from,adj,next;double len;     edge(){}     edge(int _from,int _adj,int _next,double _len):from(_from),adj(_adj),next(_next),len(_len){} } e[M]; int n,g[N],m; void AddEdge(int u,int v,double w){     e[++m]=edge(u,v,g[u],w);g[u]=m; }   double in[N]; int prep[N]; int vis[N],stamp; int bl[N],cnt; double directed_MST(){     double ret=0;     e[0].adj=0;     for (;;){         memset(in,127,sizeof(in));         memset(prep,0,sizeof(prep));         for (int u=1;u<=n;++u)             for (int i=g[u];i;i=e[i].next)                 if (e[i].len<in[e[i].adj])                     in[e[i].adj]=e[i].len,prep[e[i].adj]=u;         for (int i=1;i<=n;++i) if (prep[i]) ret+=in[i];         memset(vis,0,sizeof(vis));vis[0]=stamp=1;         memset(bl,0,sizeof(bl));cnt=0;         for (int i=1;i<=n;++i)if (!vis[i]){             int u=i;             ++stamp;             for (;!vis[u];u=prep[u]) vis[u]=stamp;             if (vis[u]==stamp){                 ++cnt;                 for (;!bl[u];u=prep[u]) bl[u]=cnt;             }         }         if (!cnt) return ret;         for (int i=1;i<=n;++i) if (!bl[i]) bl[i]=++cnt;         int m0=m;         memset(g,0,sizeof(g));m=1;         for (int i=2;i<=m0;++i)             if (bl[e[i].from]!=bl[e[i].adj])                 AddEdge(bl[e[i].from],bl[e[i].adj],e[i].len-in[e[i].adj]);         n=cnt;     } }   int need[N]; double mincost[N]; int main(){     scanf("%d",&n);++n;     memset(g,0,sizeof(g));m=1;     int u,v,m0;double tmp;     for (int i=1;i<n;++i){         scanf("%lf%d",&mincost[i],&need[i]);         if (need[i])             AddEdge(n,i,mincost[i]);     }     scanf("%d",&m0);     while (m0--){         scanf("%d%d%lf",&u,&v,&tmp);         if (need[u]&&need[v]){             AddEdge(u,v,tmp);             mincost[v]=min(mincost[v],tmp);         }     }     double sum=0;     for (int i=1;i<=n;++i)         if (need[i])             sum+=mincost[i]*(need[i]-1);     printf("%.2lf\n",sum+directed_MST());     return 0; }