オフラインリアルタイムどう書く F09 のC言語実装例 https://qiita.com/Nabetani/items/61e13fa5cf0abe5979be

yhpg_doukaku_F09.c

#include <stdio.h>
#include <string.h>

typedef char Digit;

typedef struct {
    Digit digits[3];
} Row;

typedef union {
    Digit digits[9];
    Row rows[3];
} Numbers;

typedef union {
    char string[12];
    struct {
        Row row;
        char delimiter;
    } rows[3];
} Answer;

void rotate(Numbers *numbers, int times) {
    while (--times >= 0) {
        Numbers old = *numbers;
        for (int i = 0; i < 9; i++)
            numbers->digits[i] = old.digits["741852963"[i] - '1'];
    }
}

void process(Numbers *numbers, int position) {
    rotate(numbers, position / 3);
    Row *row = &numbers->rows[position % 3];
    Row rotated = { row->digits[1], row->digits[2], row->digits[0] };
    *row = rotated;
    rotate(numbers, 4 - position / 3);
}

Answer solve(const char *positions) {
    Numbers numbers = { .digits="123456789" };
    for ( ; *positions; positions++)
        process(&numbers, *positions - 'a');
    Answer answer = { .rows={ { numbers.rows[0], '/'  },
                              { numbers.rows[1], '/'  },
                              { numbers.rows[2], '\0' } } };
    return answer;
}

void test(const char *positions, const char *expected) {
    Answer answer = solve(positions);
    printf("%s %s %s %s\n", strcmp(answer.string, expected) ? "NG" : "OK",
                            positions, expected, answer.string);
}

int main(void)
{
    /*0*/ test( "aegj", "286/435/971" );
    /*1*/ test( "a", "231/456/789" );
    /*2*/ test( "e", "183/426/759" );
    /*3*/ test( "g", "123/456/978" );
    /*4*/ test( "j", "126/459/783" );
    /*5*/ test( "bb", "123/645/789" );
    /*6*/ test( "jjj", "123/456/789" );
    /*7*/ test( "bd", "723/164/589" );
    /*8*/ test( "ah", "231/645/789" );
    /*9*/ test( "bj", "124/569/783" );
    /*10*/ test( "db", "723/561/489" );
    /*11*/ test( "dh", "723/615/489" );
    /*12*/ test( "dl", "123/456/789" );
    /*13*/ test( "hc", "123/645/897" );
    /*14*/ test( "gf", "128/453/976" );
    /*15*/ test( "hl", "623/745/189" );
    /*16*/ test( "ja", "261/459/783" );
    /*17*/ test( "ld", "123/456/789" );
    /*18*/ test( "ki", "315/486/729" );
    /*19*/ test( "lfa", "294/753/186" );
    /*20*/ test( "kga", "531/486/972" );
    /*21*/ test( "dbi", "372/561/489" );
    /*22*/ test( "che", "193/625/847" );
    /*23*/ test( "iea", "823/416/759" );
    /*24*/ test( "gbl", "523/964/178" );
    /*25*/ test( "egj", "186/425/973" );
    /*26*/ test( "jcf", "127/456/839" );
    /*27*/ test( "djh", "726/915/483" );
    /*28*/ test( "hld", "123/645/789" );
    /*29*/ test( "leeh", "453/678/129" );
    /*30*/ test( "heja", "851/629/743" );
    /*31*/ test( "cakh", "251/649/837" );
    /*32*/ test( "bhjik", "652/489/713" );
    /*33*/ test( "eabji", "483/269/751" );
    /*34*/ test( "cdbch", "823/156/974" );
    /*35*/ test( "ckgajc", "536/492/817" );
    /*36*/ test( "ggchha", "231/564/978" );
    /*37*/ test( "gfbkeg", "128/534/697" );
    /*38*/ test( "agfbcbf", "239/148/765" );
    /*39*/ test( "ekahijf", "123/645/789" );
    /*40*/ test( "hajdjbe", "789/432/615" );
    /*41*/ test( "elgililj", "976/325/814" );
    /*42*/ test( "chffefif", "317/629/845" );
    /*43*/ test( "ilbbihak", "462/587/319" );
    /*44*/ test( "abcdefghijkl", "123/456/789" );
    /*45*/ test( "hkijbglfaced", "768/125/493" );
    /*46*/ test( "dfkbjiechlga", "256/387/419" );
    /*47*/ test( "hgfkbidlajce", "186/745/239" );
    /*48*/ test( "baciefjhgkdl", "153/482/796" );
}