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 3778x 3778x 335x 335x 335x 335x 335x 3778x 3778x 3778x 3778x 3778x 3778x 3778x 3778x 3778x 3778x 3778x 494x 494x 494x 494x 335x 271x 332x 1x 1x 494x 494x 494x 494x 3778x 3778x 494x 223x 223x 3778x 3778x 3778x 3778x | /**
* @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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