Determine Whether Courses Can Be Completed
Company: Snapchat
Role: Machine Learning Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
You are given an integer `numCourses`, representing courses labeled from `0` to `numCourses - 1`, and a list `prerequisites`.
Each prerequisite is a pair `[course, prerequisite]`, meaning you must finish `prerequisite` before taking `course`.
Return `true` if it is possible to finish all courses. Return `false` if the prerequisite relationships contain a cycle that makes completion impossible.
Example:
```text
Input: numCourses = 2, prerequisites = [[1, 0]]
Output: true
Explanation: Take course 0 first, then course 1.
```
Example:
```text
Input: numCourses = 2, prerequisites = [[1, 0], [0, 1]]
Output: false
Explanation: Course 0 requires course 1, and course 1 requires course 0, so there is a cycle.
```
Expected complexity: `O(V + E)` time, where `V` is the number of courses and `E` is the number of prerequisite pairs.
Quick Answer: This question evaluates understanding of graph modeling, directed cycle detection, and dependency resolution in the context of course prerequisites. It is commonly asked in the coding & algorithms domain because it reveals a candidate's algorithmic problem-solving ability and practical application of graph algorithms (expected O(V+E) time), testing practical implementation skills rather than only conceptual theory.