Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | 2x 2x 2x 2x 2x 2x 3734x 3734x 335x 335x 335x 335x 335x 3734x 3734x 3734x 3734x 3734x 3734x 3734x 3734x 3734x 3734x 3734x 493x 493x 493x 493x 335x 272x 333x 1x 1x 493x 493x 493x 493x 3734x 3734x 493x 221x 221x 3734x 3734x 3734x 3734x | /**
* @template T
* @param {Array<[T, T]>} edges
* @returns {Array<T>|undefined}
*/
export default function check_graph_for_cycles(edges) {
/** @type {Map<T, T[]>} */
const graph = edges.reduce((g, edge) => {
const [u, v] = edge;
if (!g.has(u)) g.set(u, []);
if (!g.has(v)) g.set(v, []);
g.get(u).push(v);
return g;
}, new Map());
const visited = new Set();
const on_stack = new Set();
/** @type {Array<Array<T>>} */
const cycles = [];
/**
* @param {T} v
*/
function visit(v) {
visited.add(v);
on_stack.add(v);
graph.get(v)?.forEach((w) => {
if (!visited.has(w)) {
visit(w);
} else if (on_stack.has(w)) {
cycles.push([...on_stack, w]);
}
});
on_stack.delete(v);
}
graph.forEach((_, v) => {
if (!visited.has(v)) {
visit(v);
}
});
return cycles[0];
}
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