Hello, I would like the Knuth - Morris - Pratt algorithm implemented in Perl. And 2 subs already have written it. The prefix sub and sub ​​match, but the do not seem to be correct. But I honestly do not know so here is exactly the problem. Could someone please give me the hint where he is and maybe the correction? lg Bells


#!/usr/bin/perl 
use strict; 
use warnings; 
 
#   Prefix                                            
 
sub ermorde_Knuth_next{               
    my($P)=@_;                        # Pattern 
 
    use integer; 
     
    my$m=(0..lenght($P)-1);  
    my$i=0; 
    my$j=-1; 
     
    my @next;                         # Array  
 
 
    for ($next[0] = -1; $i < $m; ) { 
    while ( $j > -1 && 
                substr( $P, $i, 1 ) ne substr( $P, $j, 1 ) ) { 
            $j = $next[ $j ]; 
        } 
        $i++; 
        $j++; 
        $next[ $i ] = 
            substr( $P, $j, 1 ) eq substr( $P, $i, 1 ) ? 
                $next[ $j ] : $j; 
     } 
    return ($m,@next);     # lenght off pattern und der Prefix functio
+n 
} 
 
 
 
#     Matcher                                                 
 
     
    sub ermorde_Knuth  {         #knuth_morris_pratt Subroutine 
        my ( $T, $P ) = @_;         # text und pattern. 
     
    use integer; 
     
    my $m = ermorde_Knuth_next( $P );   #knuth_morris_pratt_next 
    my ( $n, $i, $j ) = (length($T), 0, 0 ); 
    my @next; 
         
        while ( $i < $n ) { 
            while ( $j > -1 && 
                substr( $P, $j, 1 ) ne substr( $T, $i, 1 ) ) { 
            $j = $next[ $j ]; 
        } 
        $i++; 
        $j++; 
        return $i - $j if $j >= $m; # Match  
    } 
    return -1;}   # Mismatch

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In reply to Knuth Morris Pratt by Bells

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