aoc/2022/06/part-one.d


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import core.stdc.stdio : getchar, printf;

extern(C) void main()
{
    slide: for (auto q = 0u, i = 1u; q & 0xffu ^ '\n'; ++i)
    {
        q <<= 8u;
        q |= getchar();
        if (i < 4)
          continue;

        auto p = cast(ubyte*) &q;
        for (auto s = 0u, j = 0u; j < 4u; ++j)
        {
            auto b = 1u << (p[j] & 0x1fu);
            if (s & b)
                continue slide;
            s |= b;
        }

        printf("%d\n", i);
        break;
    }
}