样例输入

样例输出

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstdlib>
  4 #include <cstring>
  5 #include <cmath>
  6 #include <algorithm>
  7 #define min(a, b) ((a) < (b) ? (a) : (b))
  8 #define max(a, b) ((a) > (b) ? (a) : (b))
  9
 10 inline void read(int &x)
 11 {
 12     x = 0;char ch = getchar(), c = ch;
 13     while(ch < '0' || ch > '9')c = ch, ch = getchar();
 14     while(ch <= '9' && ch >= '0')x = x * 10 + ch - '0', ch = getchar();
 15     if(c == '-')x = -x;
 16 }
 17
 18 const int INF = 0x3f3f3f3f;
 19 const int MAXN = 800 + 10;
 20
 21 int n,cost[MAXN];
 22
 23 struct Edge
 24 {
 25     int u,v,next;
 26     Edge(int _u, int _v, int _next){u = _u;v = _v;next = _next;}
 27     Edge(){}
 28 }edge[MAXN << 1];
 29
 30 int head[MAXN],cnt;
 31
 32 inline void insert(int a, int b)
 33 {
 34     edge[++cnt] = Edge(a,b,head[a]);
 35     head[a] = cnt;
 36 }
 37
 38 int fa[MAXN], dp[MAXN][3];
 39 /*
 40 dp[i][0]表示i放警卫的最小费用
 41 dp[i][1]表示i被儿子看到的最小费用
 42 dp[i][2]表示i被父亲看到的最小费用
 43
 44 dp[i][0] = Σmin(dp[son[i]][2], dp[son[i]][0],dp[son[i][1]) + cost[i]
 45 dp[i][1] = Σmin(dp[son[i]][0], dp[son[i]][1]) + dp[j][0] j从son[i]中除去
 46 dp[i][2] = Σmin(dp[son[i]][1], dp[son[i]][2])
 47 */
 48
 49 void dfs(int u)
 50 {
 51     if(!u)return;
 52     register int num = 0, v, cnt, tmp;//先更新0 2
 53     for(register int pos = head[u];pos;pos = edge[pos].next)
 54     {
 55         v = edge[pos].v;
 56         if(v == fa[u])continue;
 57         fa[v] = u;
 58         ++ num;
 59         dfs(v);
 60         dp[u][0] += min(dp[v][2], min(dp[v][0], dp[v][1]));
 61         dp[u][2] += min(dp[v][1], dp[v][0]);
 62     }
 63     if(!num)
 64     {
 65         dp[u][0] = cost[u];
 66         dp[u][1] = INF;
 67         dp[u][2] = 0;
 68         return;
 69     }
 70     dp[u][0] += cost[u];
 71     dp[u][1] = INF;
 72     for(register int i = 1;i <= num;++ i)
 73     {
 74         cnt = 1;
 75         tmp = 0;
 76         for(register int pos = head[u];pos;pos = edge[pos].next, ++ cnt)
 77         {
 78             v = edge[pos].v;
 79             if(v == fa[u])
 80             {
 81                 -- cnt;
 82                 continue;
 83             }
 84             if(cnt == i)tmp += dp[v][0];
 85             else tmp += min(dp[v][0], dp[v][1]);
 86         }
 87         dp[u][1] = min(dp[u][1], tmp);
 88     }
 89 }
 90
 91 int main()
 92 {
 93     read(n);
 94     register int root, tmp1,tmp2;
 95     for(register int i = 1;i <= n;++ i)
 96     {
 97         read(root),read(cost[root]),read(tmp1);
 98         for(register int j = 1;j <= tmp1;++ j)
 99         {
100             read(tmp2);
101             insert(root, tmp2),insert(tmp2, root);
102         }
103     }
104     dfs(root);
105     printf("%d", min(dp[root][0], dp[root][1]));
106     return 0;
107 }