void _kRingInternal()

in src/h3lib/lib/algos.c [240:267]

• 17 lines of code
• 8 McCabe index (conditional complexity)

void _kRingInternal(H3Index origin, int k, H3Index* out, int* distances,
                    int maxIdx, int curK) {
    if (origin == 0) return;

    // Put origin in the output array. out is used as a hash set.
    int off = origin % maxIdx;
    while (out[off] != 0 && out[off] != origin) {
        off = (off + 1) % maxIdx;
    }

    // We either got a free slot in the hash set or hit a duplicate
    // We might need to process the duplicate anyways because we got
    // here on a longer path before.
    if (out[off] == origin && distances[off] <= curK) return;

    out[off] = origin;
    distances[off] = curK;

    // Base case: reached an index k away from the origin.
    if (curK >= k) return;

    // Recurse to all neighbors in no particular order.
    for (int i = 0; i < 6; i++) {
        int rotations = 0;
        _kRingInternal(h3NeighborRotations(origin, DIRECTIONS[i], &rotations),
                       k, out, distances, maxIdx, curK + 1);
    }
}