Course Schedule.cpp

class Solution {
public:
    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
        vector<int> adj[numCourses];

        for(auto it: prerequisites){
            adj[it[1]].push_back(it[0]);
        }

        vector<int> inDegree(numCourses, 0);
        for(int i=0; i<numCourses; i++){
            for(auto it: adj[i]){
                inDegree[it]++;
            }
        }

        queue<int> q;
        for(int i=0; i<numCourses; i++){
            if(inDegree[i] == 0){
                q.push(i);
            }
        }
        
        int count = 0;
        while(!q.empty()){
            int node = q.front();
            q.pop();    
            count++;

            for(auto it: adj[node]){
                inDegree[it]--;

                if(inDegree[it] == 0){
                    q.push(it);
                }
            }
        }

        return (count==numCourses);
    }
};