CourseKahnAlgoleetcode207

class Solution {
    fun canFinish(numCourses: Int, prerequisites: Array<IntArray>): Boolean {
        val indegree = IntArray(numCourses)

        prerequisites.forEach{preArr->
            val dependentCourse = preArr[0]
            indegree[dependentCourse]++
        }

        val queue = LinkedList<Int>()

        indegree.forEachIndexed{index, dependencies->
            if(dependencies == 0){
                queue.add(index)
            }
        }

        if(queue.isEmpty()){
            return false
        }

        var index = 0
        while(!queue.isEmpty()){
            val courseDone = queue.remove()
            index++
            prerequisites.forEach{preArr->
                if(courseDone ==  preArr[1]){
                    val dependentCourse = preArr[0]
                    indegree[dependentCourse]--
                    if(indegree[dependentCourse] == 0){
                        queue.add(dependentCourse)
                    }
                }
            }
        }

        return index == numCourses

    }
}