Topological Sorting Time limit: 1.0 secondMemory limit: 64 MB Michael wants to win the world championship in programming and decided to study N subjects (for convenience we will number these subjects from 1 to N). Michael has worked out a study plan…

DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 866    Accepted Submission(s): 250 Problem Description A topological sort or topological ordering of a directed g…

Given an directed graph, a topological order of the graph nodes is defined as follow: For each directed edge A-->B in graph, A must before B in the order list. The first node in the order can be any node in the graph with no nodes direct to it. Find…

Topological sorting/ ordering is a linear ordering of its vertices such that for every directed edge uv from vertex u to vertex v, u comes before v in the ordering. We can conduct topological sorting only on DAG (directed acyclic graph). Therefore, t…

Find Function Optimization: After Path compression: int find(int x){ return root[x] == x ? x : (root[x] = find(root[x])); } Avoid Stack overflow: int find(int a){ while(root[a]!=a){ a=root[a]; } return a; }  Combined with rank : (Combined with the he…

一.什么是拓扑排序 在图论中,拓扑排序(Topological Sorting)是一个有向无环图(DAG, Directed Acyclic Graph)的所有顶点的线性序列.且该序列必须满足下面两个条件: 每个顶点出现且只出现一次. 若存在一条从顶点 A 到顶点 B 的路径,那么在序列中顶点 A 出现在顶点 B 的前面. 有向无环图(DAG)才有拓扑排序,非DAG图没有拓扑排序一说. 例如,下面这个图: 它是一个 DAG 图,那么如何写出它的拓扑排序呢?这里说一种比较常用的方法: 从 DAG…

定义: Topological Sorting is a method of arranging the vertices in a directed acyclic graph (DAG有向无环图) as a sequence, such that for every directed edge(u,v), 即u-> v, vertex u comes before v in the ordering 注意: A topological ordering is possible if and…

［抄题］: 现在你总共有 n 门课需要选,记为 0 到 n - 1.一些课程在修之前需要先修另外的一些课程,比如要学习课程 0 你需要先学习课程 1 ,表示为[0,1]给定n门课以及他们的先决条件,判断是否可能完成所有课程? 给定 n = 2,先决条件为 [[1,0]] 返回 true给定 n = 2,先决条件为 [[1,0],[0,1]] 返回 false ［思维问题］: 不知道为啥是图:抽象图,很多条边构造出来的图 ［一句话思路］: 拓扑排序:先统计度.边数,再把度=0的点放进queue,进…

DZY Loves Topological Sorting Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 1250    Accepted Submission(s): 403 Problem Description A topological sort or topological ordering of a directed g…

DZY Loves Topological Sorting Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5195 Description A topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for ev…