经典问题系列 覆盖半径\(1\)的最小点覆盖集 \(f[i][0]\) 表示不在此处建信号塔,但\(i\)及其子树都有信号 \(f[i][1]\) 表示在此处建信号塔,但\(i\)及其子树都有信号 \(f[i][2]\) 表示不在在此处建信号塔,但\(i\)子树都有信号,而\(i\)无信号 \(f[p][2]=\sum f[q][0]\) \(f[p][1]=\sum min(f[q][0],f[q][1],f[q][2])\) \(f[p][0]=min_q (f[q][1]+\sum_k m…

[USACO08JAN]手机网络Cell Phone Network 题目描述 Farmer John has decided to give each of his cows a cell phone in hopes to encourage their social interaction. This, however, requires him to set up cell phone towers on his N (1 ≤ N ≤ 10,000) pastures (convenie…

P2899 [USACO08JAN]手机网络Cell Phone Network 题目描述 Farmer John has decided to give each of his cows a cell phone in hopes to encourage their social interaction. This, however, requires him to set up cell phone towers on his N (1 ≤ N ≤ 10,000) pastures (co…

P2899 [USACO08JAN]手机网络Cell Phone Networ题目描述 Farmer John has decided to give each of his cows a cell phone in hopes to encourage their social interaction. This, however, requires him to set up cell phone towers on his N (1 ≤ N ≤ 10,000) pastures (conv…

题目描述 Farmer John has decided to give each of his cows a cell phone in hopes to encourage their social interaction. This, however, requires him to set up cell phone towers on his N (1 ≤ N ≤ 10,000) pastures (conveniently numbered 1..N) so they can all…

题目描述 Farmer John has decided to give each of his cows a cell phone in hopes to encourage their social interaction. This, however, requires him to set up cell phone towers on his N (1 ≤ N ≤ 10,000) pastures (conveniently numbered 1..N) so they can all…

题目大意 有一颗树,要为每个节点赋一个值\(l_i\leq a_i\leq r_i\),使得任意相邻的节点互素.然后对每个节点统计\(a_i\)在所有可能的情况中的和. \(n\leq 50,1\leq l_i\leq r_i\leq m,m=50000\) 题解 设\(f_{i,j}\)为以\(i\)为根的子树都赋了值后\(a_i=j\)的方案数.那么怎么处理\(f_v\)对\(f_i\)的贡献呢? \[ g_i=\mu(i)\sum_{i|j}f_{v,j}\\ f_{x,i}\times=…

include include include include include include define db double using namespace std; const int N=1e5+10,M=2*N; int next[M],head[N],go[M],tot; inline void add(int u,int v){ next[++tot]=head[u];head[u]=tot;go[tot]=v; next[++tot]=head[v];head[v]=tot;go…

// 树形DP CCPC网络赛 HDU5834 Magic boy Bi Luo with his excited tree // 题意:n个点的树,每个节点有权值为正,只能用一次,每条边有负权,可以走多次,问从每个点出发的最大获益 // 思路: // dp[i]: 从i点出发回到i点的最大值 // d[i][0] 从i点出发不回来的最大值 // d[i][1] 从i点出发取最大值的下一个点 // d[i][2] 从i点出发取次大值 // dfs1处理出这四个 // 然后,从1开始转移,分别DP…

Description     约翰意识到贝茜建设网络花费了他巨额的经费,就把她解雇了．贝茜很愤怒,打算狠狠报 复．她打算破坏刚建成的约翰的网络．    约翰的网络是树形的,连接着N(1≤N≤10000)个牛棚．她打算切断某一个牛棚的电源,使和这个牛棚相连的所有电缆全部中断．之后,就会存在若干子网络．为保证破坏够大,每一个子网的牛棚数不得超过总牛棚数的一半,那哪些牛棚值得破坏呢?   Solution 树形dp裸题,刷水好欢乐. Code #include<cstdio> ; int n,f[…