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Course Schedule

Given numCourses and prerequisites [a, b] meaning b must be taken before a, return True if all courses can be finished (no cycles).

Input: first line = numCourses, second = prerequisites as a:b comma-separated (or 'none').

Input:

2
1:0

Output:

True

Reasoning:

The input 2 represents the total number of courses, and 1:0 represents a prerequisite where course 1 must be taken after course 0.
We can model the courses as a graph, where each course is a node, and the prerequisites are directed edges, so 0 -> 1 means course 0 is a prerequisite for course 1.
Since there is only one edge and no cycles are present in the graph, all courses can be finished.
The absence of cycles in the graph implies that a valid order of courses exists, so the function returns True.

Editor

Python 3.13.1

0/0

Run code to see test results.