Zublicanes and Mumocrates dp[ i ][ j ][ k ] 表示 以 i 为根的子树, 占领 i 的 是 j 并且第一个人占了 i 子树的 k 个叶子节点的最小值. 然后随便d 1 d 就好了. #include<bits/stdc++.h> #define LL long long #define LD long double #define ull unsigned long long #define fi first #define se second #de…
It's election time in Berland. The favorites are of course parties of zublicanes and mumocrates. The election campaigns of both parties include numerous demonstrations on n main squares of the capital of Berland. Each of the n squares certainly can h…
题目链接: http://codeforces.com/contest/161/problem/D D. Distance in Tree time limit per test 3 secondsmemory limit per test 512 megabytes 问题描述 A tree is a connected graph that doesn't contain any cycles. The distance between two vertices of a tree is th…
Karen and Supermarket 感觉就是很普通的树形dp. dp[ i ][ 0 ][ u ]表示在 i 这棵子树中选择 u 个且 i 不用优惠券的最小花费. dp[ i ][ 1 ][ u ]表示在 i 这棵子树中选择 u 个且 i 用优惠券的最小花费. 注意这个转移总的合起来是O(n ^ 2)的. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk…
题目链接:http://codeforces.com/contest/440/problem/D D. Berland Federalization Recently, Berland faces federalization requests more and more often. The proponents propose to divide the country into separate states. Moreover, they demand that there is a…
B. Appleman and Tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Appleman has a tree with n vertices. Some of the vertices (at least one) are colored black and other vertices are color…
题目链接 Fill a DP table such as the following bottom-up: DP[v][0] = the number of ways that the subtree rooted at vertex v has no black vertex. DP[v][1] = the number of ways that the subtree rooted at vertex v has one black vertex. The recursion pseudo…
The Chocolate Spree 对拍拍了半天才知道哪里写错了.. dp[ i ][ j ][ k ]表示在 i 这棵子树中有 j 条链, 是否有链延伸上来. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #define PLI pair<LL, int> #d…
题解:先从节点1开始dfs.对于每一个节点,用一个set记录:以该点为根的子树的深度. a) 如果此节点的某个子节点打出了GG,则此节点直接打出GG. b) 若set的元素个数<=1,那么,以该点为根的子树,显然是可以缩成一条链滴!且该点为链的端点.c) 若set元素个数=2,以该点为根的子树,也可以收缩成一条链,且该点不是链的端点.此时,我们继续分类讨论. i) 该点没有父亲.我们成功找到了一条链~岂不美哉. ii) 该点有父亲,那么在链上会长出一根奇怪的东西.那我们赶紧报警,把该点赋给roo…
D - Chloe and pleasant prizes 链接 http://codeforces.com/contest/743/problem/D 题面 Generous sponsors of the olympiad in which Chloe and Vladik took part allowed all the participants to choose a prize for them on their own. Christmas is coming, so sponso…
http://codeforces.com/problemset/problem/743/D 题意:求最大两个的不相交子树的点权和,如果没有两个不相交子树,那么输出Impossible. 思路:之前好像也做过这种类型的题目啊,知道是树形DP,但是不知道怎么保证两个不相交.看别人代码之后, 在DFS回溯的时候, void dfs(int u, int fa) { sum[u] = w[u]; for(int i = head[u]; ~i; i = edge[i].nxt) { int v = e…
It's election time in Berland. The favorites are of course parties of zublicanes and mumocrates. The election campaigns of both parties include numerous demonstrations on n main squares of the capital of Berland. Each of the n squares certainly can h…
