My Attempted Algorithmic Solution to Andela Interview Question

PrereqsCourses.swift

import Foundation

var prereqsCourses = [
    ("Software Design", "Algorithms"),
    ("Foundations of Computer Science", "Operating Systems"),
    ("Computer Networks", "Computer Architecture"),
    ("Computer Architecture", "Software Design"),
    ("Algorithms", "Foundations of Computer Science"),
    ("Data Structures", "Computer Networks")
]

func getOrderedCourses(_ courses: [(preq: String, next: String)]) -> [String] {
    let firstCourse = getFirstCourse(prereqsCourses)!
    var result: [String] = [firstCourse]
    var nextCourse: String? = firstCourse

    while nextCourse != nil {
        if let course = getNextCourse(nextCourse!,
                                      courses: courses) {
            result.append(course)
            nextCourse = course
        } else {
            return result
        }
    }

    return result

    func getNextCourse(_ currentCourse: String, courses: [(String, String)]) -> String? {
        for course in courses {
            if course.0 == currentCourse {
                return course.1
            }
        }
        return nil
    }
}

func getFirstCourse(_ courses: [(String, String)]) -> String? {
    var firstCourse: String?
    let preReqs = courses.map { $0.0 }
    let coursesToBeTaken = courses.map { $0.1 }
    
    firstCourse = preReqs.first(where: { coursesToBeTaken.contains($0) == false })
    
    return firstCourse
}

let firstCourse = getFirstCourse(prereqsCourses)!

let orderedCourses = getOrderedCourses(prereqsCourses)

print("First Course:", firstCourse)
print("Ordered Courses:", orderedCourses)