207 Course Schedule
There are a total of n courses you have to take, labeled from 0 to n - 1.
Some courses may have prerequisites, for example to take course 0 you have to first take course 1,
which is expressed as a pair: [0,1]
Given the total number of courses and a list of prerequisite pairs, is it possible for you to finish all courses?
There are a total of 2 courses to take. To take course 1 you should have finished course 0.
So it is possible.
There are a total of 2 courses to take. To take course 1 you should have finished course 0,
and to take course 0 you should also have finished course 1. So it is impossible.
The input prerequisites is a graph represented by a list of edges, not adjacency matrices.
Read more about how a graph is represented.
You may assume that there are no duplicate edges in the input prerequisites.
click to show more hints.
This problem is equivalent to finding if a cycle exists in a directed graph.
If a cycle exists, no topological ordering exists and therefore it will be impossible to take all courses.
Topological Sort via DFS
A great video tutorial (21 minutes) on Coursera explaining the basic concepts of Topological Sort.
Topological sort could also be done via BFS.