207. Course Schedule

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/**
 * @param {number} numCourses
 * @param {number[][]} prerequisites
 * @return {boolean}
 */
var canFinish = function (numCourses, prerequisites) {

    const incommingEdges = new Array(numCourses).fill(0);
    const adjs = {};

    for (const [there, here] of prerequisites) {

        incommingEdges[there]++;

        if (adjs[here] === undefined) {
            adjs[here] = [];
        }
        adjs[here].push(there);
    }

    const q = [];

    for (let i = 0; i < numCourses; i++) {
        if (incommingEdges[i] === 0) {
            q.push(i);
        }
    }

    const seq = [];
    while (q.length > 0) {
        const here = q.shift();

        seq.push(here);

        const adj = adjs[here] ?? [];
        for (let i = 0; i < adj.length; i++) {
            const there = adj[i];
            incommingEdges[there] -= 1;

            if (incommingEdges[there] === 0) {
                q.push(there);
            }

        }

    }

    return seq.length === numCourses ? true : false;
};