Update: The number of matches came as a big suprise to blokhead so I like the way you consolidated results. The reason I limited the matching to a single input was because of the enormous amount of output when doing all possible matches as blokhead first asked for though I coded it to find all matches. Would your approach have changed if you were doing all matches not just one for the input provided?

Would your approach have changed if you were doing all matches not just one for the input provided?

Of necessity it would have to change a bit if it were going to look up more than one word per run. I saved a litte time by pre-filtering the pre/suffix hashes to avoid storing prefixed that would contravene the longest prefix only rules. That means those hashes are specific to the word being dealt with. To match more than one word per run, requires deferring the filtering until later.

Here's my first attempt at that. It deals with the tennis players file in under 1/3 seconds, so I've made no attempt to optimise it:

#! perl -sw
use 5.010;
use strict;
use Time::HiRes qw[ time ];
use Data::Dump qw[ pp ];

my $start = time;

die "Need words filename" unless @ARGV and -e $ARGV[ 0 ];

open WORDS, '<', $ARGV[ 0 ] or die $!;
chomp( my @words = <WORDS> );
close WORDS;

my( %pre, %suf );
for ( @words ) {
    for my $p ( 1 .. length() -1 ) {
        push @{ $pre{ substr $_, 0, $p } }, $_;
        push @{ $suf{ substr $_, - $p  } }, $_;
    }
}

for my $word ( @words ) {
    for my $p ( 1 .. length( $word ) - 1 ) {
        my $pre     = substr $word, 0, $p;
        my $prePlus = substr $word, 0, $p+1;
        my $suf     = substr $word, -( length( $word ) - $p );
        my $sufPlus = substr $word, -( length( $word ) - ( $p-1 ) );

        if( exists $pre{ $pre } and exists $suf{ $suf } ) {
            my @pre = grep{ !/^$prePlus/ } @{ $pre{ $pre } };
            next unless @pre;
            my @suf = grep{ !/$sufPlus$/ } @{ $suf{ $suf } };
            next unless @suf;

            say "$pre . $suf = $word";
            printf "\t$pre ( %s )\n", @pre <= 10
                ? join( ' ', @pre )
                : join( ' ', @pre[ 0 .. 9 ], '... ' . @pre );
            printf "\t$suf ( %s )\n", @suf <= 10
                ? join( ' ', @suf )
                : join( ' ', @suf[ 0 .. 9 ], '... ' . @suf );
        }
    }
}
printf STDERR "Took: %.2f seconds\n", time() -$start;

__END__
C:\test>759369 players.txt >nul
Took: 0.29 seconds

C:\test>759369 players.txt
a . hn = ahn
        a ( abramovic adamczak afinogenova aguilar akiki akita alawi a
+lbanese albuquerque aleksandrova ... 43 )
        hn ( mohn )
aki . ki = akiki
        aki ( akita )
        ki ( dabrowski filipovski jovanovski kitazaki lisicki miyazaki
+ solanki wozniacki )
aki . ta = akita
        aki ( akiki )
        ta ( costa konta namigata pennetta tananta yokota zanchetta )
        
...

w . ong = wong
        w ( wang wannasuk warburton washington webleysmith weidemann w
+einhold wejnert welford westbury ... 20 )
        ong ( hong jeong keothavong tangphong zhong )
wo . ng = wong
        wo ( woerle wowchuk wozniacki wozniak )
        ng ( chang cheng chuang frilling haring herring huang hwang ka
+ng king ... 16 )
woznia . cki = wozniacki
        woznia ( wozniak )
        cki ( lisicki )
woznia . k = wozniak
        woznia ( wozniacki )
        k ( antoniychuk black blank buryachok czink ewijk fink fitzpat
+rick gawlik grajdek ... 29 )
x . i = xi
        x ( xu )
        i ( akiki alawi alnabhani andrei ani appineni arai bai balducc
+i bartoli ... 93 )
x . ie = xie
        x ( xu )
        ie ( binnie delefortrie elie )
x . u = xu
        x ( xi xie )
        u ( anghelescu begu buzarnescu cadantu daniilidou dulgheru faf
+aliou georgatou gerasimou hincu ... 28 )
        
...

z . hong = zhong
        z ( zabala zafirova zagorska zahlavova zahlavovastrycova zaja 
+zakopalova zanchetta zaniewska zecpeskiric ... 17 )
        hong ( tangphong )
zh . ong = zhong
        zh ( zhang zhao zharkova zheng )
        ong ( jeong keothavong wong )
zho . ng = zhong
        zho ( zhou )
        ng ( chang cheng chuang frilling haring herring huang hwang ka
+ng king ... 16 )
zh . ou = zhou
        zh ( zhang zhao zharkova zheng )
        ou ( daniilidou fafaliou georgatou gerasimou )
zho . u = zhou
        zho ( zhong )
        u ( anghelescu begu buzarnescu cadantu dulgheru hincu hisamats
+u hsu liu lu ... 24 )
zo . ric = zoric
        zo ( zotter zovko )
        ric ( majeric njiric zecpeskiric )
Took: 3.79 seconds
[download]

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