Problem J. TriatripTime Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description The travel agency “Four Russians” is offering the new service for their clients. Unlike other agencies that only suggest one-way…

Problem J. Triatrip Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description The travel agency “Four Russians” is offering the new service for their clients. Unlike other agencies that only suggest one-way…

题目链接: http://codeforces.com/gym/100342 题意: 求三元环的个数 题解: 用bitset分别统计每个点的出度的边和入度的边. 枚举每一条边(a,b),计算以b为出度的边的终点构成的点集和以a为入度的边的起点够成的点集的交集,更新答案. 代码: #include<iostream> #include<cstring> #include<cstdio> #include<bitset> using namespace std;…

<题目链接> 题目大意:用用邻接矩阵表示一个有向图,现在让你求其中三元环的数量. 解题分析:先预处理得到所有能够直接到达每个点的集合$arrive[N]$和所有能够由当前点到达的集合$to[N]$.然后就是枚举三元环中的两个点$a,b$,然后再求$arrive[a]$与$to[b]$的交集,因为三元环中每个点都计算了一遍它所在所有三元环的数量,所以最后的答案就是所有点的交集之和/3.同时,因为$n\leq1500$,所以这里用到了bitset优化常数. #include <bits/st…

https://vjudge.net/problem/Gym-100342J 题意:给出一个邻接矩阵有向图,求图中的三元环的个数. 思路: 利用bitset暴力求解,记得最后需要/3. #include<iostream> #include<algorithm> #include<cstring> #include<cstdio> #include<vector> #include<stack> #include<queue&g…

题意:求有向图里面有多少个三元环. 思路:枚举起点A,遍历A可以到的B,然后求C的数量,C的数量位B可以到是地方X集合,和可以到A的地方Y集合的交集(X&Y). B点可以枚举,也可以遍历.(两种都试过,区别不大.) 枚举代码: #include<cstdio> #include<bitset> #include<cstdlib> #include<cstring> #include<iostream> #include<algori…

Problem C. Painting CottagesTime Limit: 2 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description The new cottage settlement is organized near the capital of Flatland. The construction company that is building the settl…

Problem A. Alien Communication Masterclass Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100610 Description Andrea is a famous science fiction writer, who runs masterclasses for her beloved readers. The most popular one is the…

Problem E. Explicit Formula Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100610 Description Consider 10 Boolean variables x1, x2, x3, x4, x5, x6, x7, x8, x9, and x10. Consider all pairs and triplets of distinct variables amon…

Problem F "Folding" Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100002 Description Bill is trying to compactly represent sequences of capital alphabetic characters from 'A' to 'Z' by folding repeating subsequences insid…