function deflate(obj) {
    function _deflate(obj, _sofar = new Map(), _cur_ref = [0]) {
        if (obj === null || typeof obj !== 'object') {
            return obj;
        }

        if (Array.isArray(obj)) {
            return obj.map(v => _deflate(v, _sofar, _cur_ref));
        }

        const id = obj['#id'] || Symbol('id');
        obj['#id'] = id;

        if (!_sofar.has(id)) {
            _sofar.set(id, {});
        } else {
            const flat = _sofar.get(id);
            if (flat["#"] === undefined) {
                _cur_ref[0] += 1;
                flat["#"] = _cur_ref[0];
            }
            return {"#": flat["#"]};
        }
        
        const cleaned = Object.fromEntries(Object.entries(obj).map(([k, v]) => 
            [(k.match(/^#+$/) ? '#' + k : k), _deflate(v, _sofar, _cur_ref)]));
        Object.assign(_sofar.get(id), cleaned);
        
        return _sofar.get(id);
    }

    return _deflate(obj);
}

function inflate(obj) {
    function _inflate(obj, _refs = {}) {
        if (obj === null || typeof obj !== 'object') {
            return obj;
        }

        if (Array.isArray(obj)) {
            return obj.map(v => _inflate(v, _refs));
        }

        let ref_id = null;
        if ("#" in obj) {
            ref_id = obj["#"];
            if (!(_refs[ref_id])) {
                _refs[ref_id] = {};
            }
        }

        const cleaned = Object.fromEntries(Object.entries(obj).filter(([k, v]) => k !== "#").map(([k, v]) =>
            [(k.startsWith('#') ? k.substring(1) : k), _inflate(v, _refs)]));
        
        if (ref_id === null) {
            return cleaned;
        }

        Object.assign(_refs[ref_id], cleaned);
        return _refs[ref_id];
    }

    return _inflate(obj);
}

function test() {
    const a = {"#": "collide", "##": "collide"};
    a["b"] = a;
    a["c"] = [a, a];
    a["d"] = { "e": a, "f": [a, a] };
    a["g"] = { "h": { "i": a, "j": [a, a] } };

    const a2 = inflate(JSON.parse(JSON.stringify(deflate(a), null, 2)));

    console.assert(JSON.stringify(a) === JSON.stringify(a2), 'Test failed');
}

test();