题目链接:http://codeforces.com/problemset/problem/687/A 题意:给出一个n个点m条边的图,分别将每条边连接的两个点放到两个集合中,输出两个集合中的点,若不可能则输出-1: 思路:通过画图我们不难发现,图中没有出现长度为奇数的环则是可行的,反之则是不行的． 对于这点我们可以直接用dfs搜索+染色,对于当前标记为1的点,我们将其所有儿子标记为2, 对于当前标记为2的点,将其所有儿子标记为1,若出现某个节点的标记与其儿子相同,则有长度为奇数的环. 代码:…

C. NP-Hard Problem time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Recently, Pari and Arya did some research about NP-Hard problems and they found the minimum vertex cover problem very int…

C. NP-Hard Problem 题目连接: http://www.codeforces.com/contest/688/problem/C Description Recently, Pari and Arya did some research about NP-Hard problems and they found the minimum vertex cover problem very interesting. Suppose the graph G is given. Subs…

https://codeforces.com/contest/1139/problem/E 题意 有n个学生,m个社团,每个学生有一个\(p_i\)值,然后每个学生属于\(c_i\)社团, 有d天,每天首先随机去除一个人,然后再从每个社团挑选一个学生(假如社团没有学生就跳过这个社团),使得这些学生组成的集合的mex值最大,输入每天的mex值 题解 假如这道题发现是二分图匹配就很好做 左边用\(p_i\)建点,右边用\(c_i\)建点,\(p_i\)从小到达和源点连边,然后跑个二分图匹配or最大流…

A. Maze 题目连接: http://codeforces.com/contest/377/problem/A Description Pavel loves grid mazes. A grid maze is an n × m rectangle maze where each cell is either empty, or is a wall. You can go from one cell to another only if both cells are empty and h…

C. Xor-tree Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/430/problem/C Description Iahub is very proud of his recent discovery, propagating trees. Right now, he invented a new tree, called xor-tree. After this new revolu…

一道很巧妙的二分图的题目 简单分析性质可知,一个合法序列一定是由12,21这样的子串构成的,所以相邻的每隔2个两两配对 然后BF和GF互相配对,思考一下,如果存在奇环,那么必定有一个BG有两个GF,或者一个GF有两个BF,所以不存在这种情况,一定有解 直接二分图判断即可 #include <iostream> #include <cstdio> #include <vector> #define mp make_pair #define fi first #define…

D. MADMAX time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output As we all know, Max is the best video game player among her friends. Her friends were so jealous of hers, that they created an actu…

B. Mahmoud and Ehab and the bipartiteness time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Mahmoud and Ehab continue their adventures! As everybody in the evil land knows, Dr. Evil likes bi…

题目链接:http://codeforces.com/contest/767/problem/C 题解:类似于提着一串葡萄,用剪刀剪两条藤,葡萄分成了三串.问怎样剪才能使三串葡萄的质量相等. 首先要做的就是统计葡萄的总质量tot.之后就是找到两子串质量为(tot/3)的葡萄(如果除不尽,则必定找不到),那么剩下的就是dfs搜索了. 我一开始的做法是先建一棵记录子树质量和的树,然后再从上往下dfs,如果找到了,就把它剪掉.后来发现被剪掉的那一串可能就含有两串质量为(tot/3)的葡萄(这里质量 可…

题意:给出一棵树,共有n个节点,其中根节点是Kefa的家,叶子是restaurant,a[i]....a[n]表示i节点是否有猫,问:Kefa要去restaurant并且不能连续经过m个有猫的节点有多少条路径: 思路:先用vector数组建树: 再dfs..(第一次用vector建树,还看了别人的代码,果然是zz): 代码: #include <bits/stdc++.h> #define ll long long #define MAXN 100000+10 using namespace…

每次AB秒出 到了C难度陡然上升...翻译都弄不懂... C 给出一张图 找出两个点的覆盖集(覆盖集是指这图中每条边都有至少一个点在这个点集里面) 并且两个点集没有交集 英文很难看懂...就是二分图的判定 看看这张图是不是二分图 输出两边的点 不是二分图输出-1 坑点是这是special judge 但是题目没说 每个联通块都要进行一次bfs 那些独立点可以不输出也可以随意分配 D 给出k与n个数ci 我们知道一个未知的数x%ci的数 问能不能求出x%k的数 可以利用中国剩余定理来解 如果我们知…

D. Fedor and Essay time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output After you had helped Fedor to find friends in the «Call of Soldiers 3» game, he stopped studying completely. Today, the E…

D. Dividing Kingdom II 题目连接: http://www.codeforces.com/contest/687/problem/D Description Long time ago, there was a great kingdom and it was being ruled by The Great Arya and Pari The Great. These two had some problems about the numbers they like, so…

D. Remainders Game 题目连接: http://www.codeforces.com/contest/688/problem/D Description Today Pari and Arya are playing a game called Remainders. Pari chooses two positive integer x and k, and tells Arya k but not x. Arya have to find the value . There…

B. Lovely Palindromes 题目连接: http://www.codeforces.com/contest/688/problem/B Description Pari has a friend who loves palindrome numbers. A palindrome number is a number that reads the same forward or backward. For example 12321, 100001 and 1 are palin…

A. Opponents 题目连接: http://www.codeforces.com/contest/688/problem/A Description Arya has n opponents in the school. Each day he will fight with all opponents who are present this day. His opponents have some fighting plan that guarantees they will win…

#include<bits/stdc++.h>using namespace std;const int N=200005;int n,A[N];long long Mx,tot,S[N];vector<int>Adj[N];void DFS(int v,int p){    S[v]=A[v];    for(int &u:Adj[v])        if(u!=p)            DFS(u,v),S[v]+=S[u];    if(p)//0号结点是不存在的…

D. Dividing Kingdom II   Long time ago, there was a great kingdom and it was being ruled by The Great Arya and Pari The Great. These two had some problems about the numbers they like, so they decided to divide the great kingdom between themselves. Th…

E. The Values You Can Make     Pari wants to buy an expensive chocolate from Arya. She has n coins, the value of the i-th coin is ci. The price of the chocolate is k, so Pari will take a subset of her coins with sum equal to k and give it to Arya. Lo…

题目链接: 题目 E. The Values You Can Make time limit per test:2 seconds memory limit per test:256 megabytes 问题描述 Pari wants to buy an expensive chocolate from Arya. She has n coins, the value of the i-th coin is ci. The price of the chocolate is k, so Pari…

题目链接: 题目 D. Remainders Game time limit per test 1 second memory limit per test 256 megabytes 问题描述 Today Pari and Arya are playing a game called Remainders. Pari chooses two positive integer x and k, and tells Arya k but not x. Arya have to find the v…

---恢复内容开始--- Kurt reaches nirvana when he finds the product of all the digits of some positive integer. Greater value of the product makes the nirvana deeper. Help Kurt find the maximum possible product of digits among all integers from 1 to n. Input…

D. Remainders Game time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Today Pari and Arya are playing a game called Remainders. Pari chooses two positive integer x and k, and tells Arya k but…

链接: https://codeforces.com/contest/1228/problem/D 题意: You have a simple undirected graph consisting of n vertices and m edges. The graph doesn't contain self-loops, there is at most one edge between a pair of vertices. The given graph can be disconne…

题目传送门 /* 题意:告诉起点终点,踩一次, '.'变成'X',再踩一次,冰块破碎,问是否能使终点冰破碎 DFS:如题解所说,分三种情况:1. 如果两点重合,只要往外走一步再走回来就行了:2. 若两点相邻, 那么要不就是踩一脚就破了或者踩一脚走开再走回来踩一脚破了:3. 普通的搜索看是否能到达, 若能还是要讨论终点踩几脚的问题:) DFS 耗时大,险些超时,可以用BFS来做 */ #include <cstdio> #include <algorithm> #include &l…

题目传送门 /* 题意:两点之间有不同颜色的线连通,问两点间单一颜色连通的路径有几条 DFS:暴力每个颜色,以u走到v为结束标志,累加条数 注意:无向图 */ #include <cstdio> #include <iostream> #include <algorithm> #include <cstring> #include <string> #include <vector> using namespace std; ; co…

题目传送门 /* DFS: 排序后一个一个出发往后找,找到>r为止,比赛写了return : */ #include <cstdio> #include <iostream> #include <cstring> #include <cmath> #include <algorithm> #include <vector> #include <map> #include <queue> #include…

题目传送门 /* DFS:按照长度来DFS,最后排序 */ #include <cstdio> #include <algorithm> #include <cstring> #include <iostream> #include <cmath> #include <vector> using namespace std; ; const int INF = 0x3f3f3f3f; ] = {, }; int a[MAXN]; in…

Codeforces Round #622 (Div. 2) A. Fast Food Restaurant 题意: 你是餐馆老板,虽然只会做三道菜,上菜时还有个怪癖:一位客人至少上一道菜,且一种菜最多上一次,所有客人菜单不能相同.给出三种菜的数量,问最多能接收多少客人. 思路: 一人一道 → 一人两道 → 一人三道. #include <bits/stdc++.h> using namespace std; int main() { int t;cin>>t; while(t--…