题目链接:375D - Tree and Queries 题目大意:给你一个有n个点的树,每个点都有其对应的颜色,给出m次询问(v,k),问v的子树中有多少种颜色至少出现k次 题解:先对所有的询问进行分类,即对所有相同的v合并到一起,这样就能转为离线处理(更新每个点的状态时同时求出答案) 开两个map<int,int>,cnt[i][j]表示 i 节点的子树中 j 颜色出现了多少次,f[i][j]则表示 i 节点的子树中至少出现 j 次的颜色个数.dfs的时候暴力枚举所有颜色合并能够得出正确答…

Codeforces Round #499 (Div. 1) F. Tree 题目链接 \(\rm CodeForces\):https://codeforces.com/contest/1010/problem/F Solution 设\(v_i\)表示第\(i\)个点的果子数,设\(b_i=v_i-\sum_{x\in son}v_x\),显然依题意要满足\(b_i\geqslant 0\). 根据差分的性质我们可以得到\(\sum b_i=x\). 假设我们硬点树上剩下了\(m\)个点,则…

题目传送门 /* 递推:用cnt记录前缀值,查询区间时,两个区间相减 */ #include <cstdio> #include <algorithm> #include <cmath> #include <cstring> using namespace std; ; const int INF = 0x3f3f3f3f; char s[MAXN]; int cnt[MAXN]; int main(void) //Codeforces Round #186…

D. Tree Requests time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a lowercase English letter. Vertex 1 is the root of the…

题目链接: http://codeforces.com/contest/675/problem/D 题意: 给你一系列点,叫你构造二叉搜索树,并且按输入顺序输出除根节点以外的所有节点的父亲. 题解: n有10^5,如果直接去建树,最会情况会O(n^2)t掉. 因此我们需要利用一些二叉搜索树的性质: 对于当前输入节点v,找出已经输入的最大的l和最小的r使得l<v<r. 由于输入v之前l和r中间是没有数的,所以l和r必定为祖先和后代的关系,如果不是的话,就会导致l和r中间还有数(l和r的公共祖先)…

https://codeforces.com/contest/1118/problem/F1 #include<bits/stdc++.h> using namespace std; int n; vector<int> color; vector<vector<int> > tree; ,blue=; ; pair<){ ); ); ;i<tree[v].size();i++){ int u=tree[v][i]; if(u!=p){//避免回…

D. Tree Construction 题目连接: http://www.codeforces.com/contest/675/problem/D Description During the programming classes Vasya was assigned a difficult problem. However, he doesn't know how to code and was unable to find the solution in the Internet, so…

任意门:http://codeforces.com/contest/1118/problem/F1 F1. Tree Cutting (Easy Version) time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given an undirected tree of nn vertices. Some vert…

传送门:http://codeforces.com/contest/1092/problem/F F. Tree with Maximum Cost time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a tree consisting exactly of nn vertices. Tree is a…

Tree Construction Problem's Link ---------------------------------------------------------------------------- Mean: 给定n个数,按照构造Binary Search Tree的方式来构造BST树,按顺序输出每一个非root结点的父节点的值. analyse: 构造BST树最坏情况下时间复杂度为O(n),肯定会超时. 注意到只需要输出结点的父节点的值,不需要真的构造BST树. 插到第i…