Codefoces 791D. Bear and Tree Jumps 树形DP

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Codefoces 791D. Bear and Tree Jumps 树形DP

D. Bear and Tree Jumps A tree is an undirected connected graph without cycles. The distance between two vertices is the number of edges in a simple path between them. Limak is a little polar bear. He lives in a tree that consists of n vertices, num…

CodeForces 771C Bear and Tree Jumps 树形DP

题意: 给出一棵树,一个人可以在树上跳,每次最多跳$k(1 \leq k \leq 5)$个点定义$f(s,t)$为从顶点$s$跳到顶点$t$最少需要跳多少次求$\sum\limits_{s<t}f(s,t)$ 分析: 注意到$k$很小,为了方便转移,定义: $sz(u,i)$为$u$的子树中与$u$的距离模$k$等于$i$的孩子节点的个数 $d(u,i)$为从$u$跳到$sz(u,i)$对应的节点的跳数之和转移: \(sz(u,(i…

Codeforces 791D Bear and Tree Jump（树形DP）

题目链接 Bear and Tree Jumps 考虑树形DP.$c(i, j)$表示$i$最少加上多少后能被$j$整除. 在这里我们要算出所有$c(i, k)$的和. 其中$i$代表每个点对的距离,$k$为输入的$k$值. $f[i][j]$表示以$i$为根结点,深度对$k$取模为$j$的点的个数. 状态转移时$f[x][i]$一边更新一边和刚刚计算出的$f[u][j]$统计答案. 具体细节可以看代码. #include <bits/stdc++.h> using namespace std…

[CF791D]Bear and Tree Jumps

题目描述 A tree is an undirected connected graph without cycles. The distance between two vertices is the number of edges in a simple path between them. Limak is a little polar bear. He lives in a tree that consists of n vertices, numbered 1 through n. L…

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Codeforces Round #263 (Div. 2) D. Appleman and Tree（树形DP）

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