P3047 [USACO12FEB]附近的牛Nearby Cows 题目描述 Farmer John has noticed that his cows often move between nearby fields. Taking this into account, he wants to plant enough grass in each of his fields not only for the cows situated initially in that field, but…

传送门 解题思路 树形dp,看到数据范围应该能想到是O(nk)级别的算法,进而就可以设出dp状态,dp[x][j]表示以x为根的子树,距离它为i的点的总和,第一遍dp首先自底向上,dp出每个节点的子树中到他距离为j的,转移方程dp[x][j]=dp[u][j-1] ,第二遍dp自顶向下,dp出每个节点父亲那头的距离为j的,转移方程dp[u][j]+=dp[x][j-1]-dp[u][j-2] 代码 //dp[x][j] 以i为根的子树,距离为j的牛的和 //dp[x][j]+=dp[u][j-1…

题目描述 Farmer John has noticed that his cows often move between nearby fields. Taking this into account, he wants to plant enough grass in each of his fields not only for the cows situated initially in that field, but also for cows visiting from nearby…

https://www.luogu.org/problemnew/show/P304 1 #include <bits/stdc++.h> 2 #define up(i,l,r) for(register int i = (l); i <= (r); ++i) 3 #define dn(i,l,r) for(register int i = (l); i >= (r); --i) 4 #define ll long long #define re register using na…

P3047 [USACO12FEB]附近的牛Nearby Cows 题目描述 Farmer John has noticed that his cows often move between nearby fields. Taking this into account, he wants to plant enough grass in each of his fields not only for the cows situated initially in that field, but…

P3047 [USACO12FEB]附近的牛Nearby Cows 农民约翰已经注意到他的奶牛经常在附近的田野之间移动.考虑到这一点,他想在每一块土地上种上足够的草,不仅是为了最初在这片土地上的奶牛,而且是为了从附近的田地里去吃草的奶牛. 具体来说,FJ的农场由N块田野构成(1 <= n <= 100,000),每两块田野之间有一条无向边连接(总共n-1条边).FJ设计了农场,任何两个田野i和j之间,有且只有一条路径连接i和j.第 i块田野是C(i)头牛的住所,尽管奶牛们有时会通过k条路到达其…

洛谷P2014 选课 题目描述 在大学里每个学生,为了达到一定的学分,必须从很多课程里选择一些课程来学习,在课程里有些课程必须在某些课程之前学习,如高等数学总是在其它课程之前学习.现在有N门功课,每门课有个学分,每门课有一门或没有直接先修课(若课程a是课程b的先修课即只有学完了课程a,才能学习课程b).一个学生要从这些课程里选择M门课程学习,问他能获得的最大学分是多少? 输入输出格式 输入格式: 第一行有两个整数N,M用空格隔开.(1<=N<=300,1<=M<=300) 接下来的…

题目描述 Farmer John has noticed that his cows often move between nearby fields. Taking this into account, he wants to plant enough grass in each of his fields not only for the cows situated initially in that field, but also for cows visiting from nearby…

题面 题目描述 Farmer John has noticed that his cows often move between nearby fields. Taking this into account, he wants to plant enough grass in each of his fields not only for the cows situated initially in that field, but also for cows visiting from nea…

$k$ 十分小,直接暴力维护 $1$~$k$ 的答案即可. 然后需要用父亲转移到儿子的方式转移一下. Code: #include <bits/stdc++.h> #define M 23 #define N 100005 #define setIO(s) freopen(s".in","r",stdin) using namespace std; int n,K,edges; int f[N][M],hd[N],to[N<<1],nex[N…