json_problem.py

json_problem.py

def serialize(o):
    if isinstance(o, int):
        return str(o)
    else:
        return '[' + ','.join(serialize(e) for e in o) + ']'


def deserialize(s):
    idx = 0
    def parse_list(s):
        nonlocal idx
        ret = []
        while idx < len(s):
            v = s[idx]
            if v.isnumeric():
               num = parse_number(s)
               ret.append(num)
            elif v == '[':
               idx +=1
               parsed_list = parse_list(s)
               ret.append(parsed_list)
            elif v == ']':
                idx += 1
                return ret
            else:
                idx += 1
        return ret

    def parse_number(s):
        nonlocal idx
        number = 0
        while idx < len(s):
            v = s[idx]
            if v.isnumeric():
                number *= 10
                number += int(v)
                idx += 1
            else:
                return number
        return number

    ret = parse_list(s)
    return ret[0]


def main():
    test_cases = [
        "345",
        "[]",
        "[[[]]]",
        "[[],[[]]]",
        "[1,2,3]",
        "[1,2,[3]]",
        "[1,[2],3]",
        "[1,[2,[3,4,[5]]]]",
    ]
    for t in test_cases:
        passed = serialize(deserialize(t)) == t
        print(f"{'PASS' if passed else 'FAIL'}: {t}")


if __name__ == '__main__':
    main()