第五回オフラインリアルタイムどう書くの回答例(C99)

// use "-std=c99"
# include <stdio.h>
# include <stdlib.h>
# include <memory.h>
# include <string.h>

int strength( char const * c )
{
    char rep = c[1];
    char m[]="3456789TJQKA2o";
    return strchr( m, rep ) - m;
}
int strengthm( char const * c )
{
    int jo = strength( "Jo");
    int cand = strength( c);
    if ( cand == jo ){
        return strength( c+2);
    } else {
        return cand;
    }
}

char const * dahi_1( char const * f, char const * inHand )
{
    int hc = strlen( inHand )/2;
    char const * ret=calloc( hc*3+3, 1 );
    int fs = strength( f );
    for( int h=0 ; h<hc ; ++h ){
        if ( fs < strength( inHand+h*2)){
            if ( *ret ){
                strcat( ret, ",");
            }
            strncat( ret, inHand+h*2, 2 );
        }
    }
    if ( *ret==0 ){
        strcat( ret, "-");
    }
    return ret;
}
int legal( char const * c )
{
    char const * end = c+strlen( c );
    int jo = strength( "Jo");
    int s=0;
    for( char const * p=c ; p<end ; p+=2 ){
        int sc=strength( p );
        if ( sc==jo ){
            continue;
        }
        if ( s==0 ){
            s=sc;
        } else {
            if ( s!=sc ){
                return 0;
            }
        }
    }
    return 1;
}
char const * dahi_2( char const * f, char const * inHand )
{
    int hc = strlen( inHand )/2;
    char cand[5]={0};
    char const * ret=calloc( hc*hc*3+9, 1 );
    int fs = strengthm( f );
    for( int h=0 ; h<hc ; ++h ){
        for( int h1=0 ; h1<h ; ++h1 ){
            memset( cand, 0, sizeof(cand) );
            strncat( cand, inHand+h*2, 2);
            strncat( cand, inHand+h1*2, 2);
            if ( legal( cand ) && fs < strengthm( cand )){
                if ( *ret ){
                    strcat( ret, ",");
                }
                strcat( ret, cand );
            }
        }
    }
    if ( *ret==0 ){
        strcat( ret, "-");
    }
    return ret;
}
char const * dahi_3( char const * f, char const * inHand )
{
    int hc = strlen( inHand )/2;
    char cand[7]={0};
    char const * ret=calloc( hc*hc*hc*7+9, 1 );
    int fs = strengthm( f );
    for( int h=0 ; h<hc ; ++h ){
        for( int h1=0 ; h1<h ; ++h1 ){
            for( int h2=0 ; h2<h1 ; ++h2 ){
                memset( cand, 0, sizeof(cand) );
                strncat( cand, inHand+h*2, 2);
                strncat( cand, inHand+h1*2, 2);
                strncat( cand, inHand+h2*2, 2);
                if ( legal( cand ) && fs < strengthm( cand )){
                    if ( *ret ){
                        strcat( ret, ",");
                    }
                    strcat( ret, cand );
                }
            }
        }
    }
    if ( *ret==0 ){
        strcat( ret, "-");
    }
    return ret;
}
char const * dahi_4( char const * f, char const * inHand )
{
    int hc = strlen( inHand )/2;
    char cand[9]={0};
    char const * ret=calloc( hc*hc*hc*hc*9+9, 1 );
    int fs = strengthm( f );
    for( int h=0 ; h<hc ; ++h ){
        for( int h1=0 ; h1<h ; ++h1 ){
            for( int h2=0 ; h2<h1 ; ++h2 ){
                for( int h3=0 ; h3<h2 ; ++h3 ){
                    memset( cand, 0, sizeof(cand) );
                    strncat( cand, inHand+h*2, 2);
                    strncat( cand, inHand+h1*2, 2);
                    strncat( cand, inHand+h2*2, 2);
                    strncat( cand, inHand+h3*2, 2);
                    if ( legal( cand ) && fs < strengthm( cand )){
                        if ( *ret ){
                            strcat( ret, ",");
                        }
                        strcat( ret, cand );
                    }
                }
            }
        }
    }
    if ( *ret==0 ){
        strcat( ret, "-");
    }
    return ret;
}
char const * solve( char const * in )
{
    char * f = strdup( in ); // TODO: memory leak!
    char * inHand = strchr( f, ',' )+1;
    inHand[-1]=0;

    int cardCount = strlen( f )/2;
    switch( cardCount ){
        case 1:
            return dahi_1( f, inHand );
        case 2:
            return dahi_2( f, inHand );
        case 3:
            return dahi_3( f, inHand );
        case 4:
            return dahi_4( f, inHand );
        default:
        return strdup("-");
    }
}
int is_same( char const * a, char const * b )
{
    // 不十分にも程があるが、時間の都合でこの程度で我慢した。
    return  strlen(a) == strlen(b);
}

void test( char const * in, char const * expected )
{
    char const * ac = solve( in );
    if ( ! is_same( ac, expected) ){
        puts( "**FAIL**");
    }
    printf( " : %s\n    %s\n    %s\n", in, ac, expected );
    free( ac );
}

int main()
{
    /*#1*/ test( "DJ,", "-" );
    /*#2*/ test( "H7,HK", "HK" );
    /*#17*/ test( "JoC8,H6D7C5S9CQH9STDTCAD9S5DAS2CT", "CTDT,H9D9,S9D9,DACA,CTST,H9S9,DTST" );
    /*#22*/ test( "D8H8S8,CQHJCJJoHQ", "JoCQHQ,JoHJCJ" );
    /*#28*/ test( "H5C5S5D5,C7S6D6C3H7HAH6H4C6HQC9", "C6D6S6H6" );
    /*#32*/ test( "JoS8D8H8,S9DTH9CTD9STC9CAC2", "H9C9D9S9" );
    // テストの大半を省略
    return 0;
}