LeetCode-Java/Course Schedule at main · dhinith2007/LeetCode-Java · GitHub

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LEETCODE PROBLEM SOLVING
PROBLEM->COURSE SCHEDULE
import java.util.*;

class Solution {

    public boolean canFinish(int numCourses,
                             int[][] prerequisites) {
        List<List<Integer>> graph =
            new ArrayList<>();

        for (int i = 0; i < numCourses; i++) {
            graph.add(new ArrayList<>());
        }
        int[] indegree = new int[numCourses];
        for (int[] pre : prerequisites) {

            int course = pre[0];
            int prereq = pre[1];

            graph.get(prereq).add(course);

            indegree[course]++;
        }
        Queue<Integer> queue =
            new LinkedList<>();

        for (int i = 0; i < numCourses; i++) {

            if (indegree[i] == 0) {
                queue.offer(i);
            }
        }

        int completed = 0;

        while (!queue.isEmpty()) {

            int current = queue.poll();

            completed++;

            for (int neighbor :
                 graph.get(current)) {

                indegree[neighbor]--;

                if (indegree[neighbor] == 0) {
                    queue.offer(neighbor);
                }
            }
        }

        return completed == numCourses;
    }
}