Course Schedule IV

				
					/** 
 * @param {number} numCourses 
 * @param {number[][]} prerequisites 
 * @param {number[][]} queries 
 * @return {boolean[]} 
 */
var checkIfPrerequisite = function(numCourses, prerequisites, queries) {
    // Adjacency list banate hain har course ke prerequisites ko store karne ke liye
    const adj = Array.from({length: numCourses}, () => []);
    const indegree = new Array(numCourses).fill(0); // Indegree array initialize karte hain

    // Prerequisites ko adjacency list aur indegree array mein add karte hain
    for(let p of prerequisites) {
        adj[p[0]].push(p[1]);
        indegree[p[1]]++;
    }

    const q = [];
    // Queue ko un courses se initialize karte hain jinke koi prerequisites nahi hain (leaf nodes)
    for(let i = 0; i < numCourses; i++) {
        if(indegree[i] === 0) {
            q.push(i);
        }
    }

    const mp = new Map(); // Map to store all prerequisites for each course
    // Har course ka ek new set create karte hain
    for(let i = 0; i < numCourses; i++) {
        mp.set(i, new Set());
    }

    // Processing the courses using Kahn's algorithm
    while(q.length > 0) {
        const curr = q.shift(); // Queue se current course nikalte hain
        for(let next of adj[curr]) { // Har adjacent course ke liye
            mp.get(next).add(curr); // Direct prerequisite add karte hain
            for(let pre of mp.get(curr)) { // Indirect prerequisites bhi add karte hain
                mp.get(next).add(pre);
            }
            indegree[next]--; // Indegree update karte hain
            if(indegree[next] === 0) { // Agar next course ke prerequisites complete ho gaye hain
                q.push(next); // Queue mein add karte hain
            }
        }
    }

    // Answering the queries by checking the map
    return queries.map(([u, v]) => mp.get(v).has(u)); // Agar prerequisite hai to true, otherwise false
};