package top100liked

// https://leetcode.cn/problems/course-schedule/?envType=study-plan-v2&envId=top-100-liked

import "slices"

func canFinish(numCourses int, prerequisites [][]int) bool {
	adjacencyList := make([][]int, numCourses)
	for _, prerequisit := range prerequisites {
		from, to := prerequisit[1], prerequisit[0]
		adjacencyList[from] = append(adjacencyList[from], to)
	}

	state := make([]int, numCourses)

	var hasCycle func(int) bool
	hasCycle = func(node int) bool {
		if state[node] == 1 {
			return true
		}
		if state[node] == 2 {
			return false
		}
		state[node] = 1
		if slices.ContainsFunc(adjacencyList[node], hasCycle) {
			return true
		}
		state[node] = 2
		return false
	}

	for i := 0; i < numCourses; i++ {
		if hasCycle(i) {
			return false
		}
	}

	return true
}