题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5647 题解: 令dp[u][0]表示u所在的子树中所有的包含i的集合数,设u的儿子为vi,则易知dp[u][0]=(dp[v1][0]+1)*...*(dp[vk][0]+1). 令dp[u][1]表示u所在的子树中所有的包含i的集合数的大小的和,则有dp[u][1]=dp[u][1]*(dp[v][0]+1)+dp[v][1]*dp[u][0]: 其中dp[u][1]*(dp[v][0]+1)表…

(先奉上jcvb大神的官方题解)BC 76 div 1 1002 对于每个结点i,统计出f[i]表示包含i的连通集有多少个,那么容易看出答案就是所有f[i]的和. 要计算f[i]是经典的树形DP问题.令g[i]表示以i为根的连通集的数目,那么g[i]=∏(g[j]+1), j是i的儿子,按这个从下往上DP一遍. 然后再用同样的式子从上往下DP一遍就好了.这一步骤写的时候要注意一下不要写错. 时间复杂度O(n). 然后本蒟蒻不会这么写,因为一些人说需要逆元,而且这个题卡逆元,所以果断没有写 然后果…

pid=5647">[HDU 5647]DZY Loves Connecting(树DP) DZY Loves Connecting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others) Total Submission(s): 332    Accepted Submission(s): 112 Problem Description DZY has an unroote…

题目链接: hdu:http://acm.hdu.edu.cn/showproblem.php?pid=5646 bc:http://bestcoder.hdu.edu.cn/contests/contest_chineseproblem.php?cid=680&pid=1002 DZY Loves Connecting Accepts: 16     Submissions: 169 Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 26…

Hdu 5274 Dylans loves tree (树链剖分模板) 题目传送门 #include <queue> #include <cmath> #include <cstdio> #include <cstring> #include <cstdlib> #include <iostream> #include <algorithm> #include <vector> #define ll long…

DZY Loves Topological Sorting Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5195 Description A topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for ev…

传送门 DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 221    Accepted Submission(s): 52 Problem Description A topological sort or topological ordering of a directed…

DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 1250    Accepted Submission(s): 403 Problem Description A topological sort or topological ordering of a directed g…

DZY Loves Sorting Time Limit: 12000/6000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 753    Accepted Submission(s): 249 Problem Description DZY has a sequence a[1..n]. It is a permutation of integers 1∼n. Now h…

DZY Loves Sorting Time Limit: 12000/6000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 294    Accepted Submission(s): 77 Problem Description DZY has a sequence a[1..n]. It is a permutation of integers 1∼n. Now he…