Code Golf: Connecting the dots

Answer 1

Powershell, 328 304 characters

$i=$l=0;$k=@{}
$s=@($input|%{[regex]::matches($_,"\d+")|%{$k[1*$_.Value]=@{y=$l
x=$_.Index}};$l++;""})
while($a=$k[++$i]){
if($i-eq1){$x=$a.x;$y=$a.y}
do{$d=$a.x.CompareTo($x);$e=$a.y.CompareTo($y)
$s[$y]=$s[($y+=$e)].PadRight($x+1).Remove($x,1).Insert(($x+=$d),
"\-/|+|/-\"[4+$d*3+$e])}while($d-or$e)}$s

and here's a pretty-printed version with comments:

# Usage: gc testfile.txt | dots.ps1

$l=$i=0            # line, dot index (used below)
$k=@{}             # hashtable that maps dot index to coordinates  

# Apply regular expression to each line of the input
$s=@( $input | foreach{     
        [regex]::matches($_,"\d+") | foreach{
            # Store each match in the hashtable
            $k[ 1*$_.Value ] = @{ y = $l; x = $_.Index }
        }
        $l++; # Next line
        ""    # For each line return an empty string.
              # The strings are added to the array $s which
              # is used to produce the final output
    }
)

# Connect the dots!
while( $a = $k[ ++$i ] )
{
    if( $i -eq 1 )  # First dot?
    {
        # Current position is ($x, $y)
        $x = $a.x;
        $y = $a.y
    }

    do
    {
        $d = $a.x.CompareTo( $x )           # sign( $a.x - $x )
        $e = $a.y.CompareTo( $y )           # sign( $a.y - $y )
        $c = '\-/|+|/-\'[ 4 + $d * 3 + $e ] # character            '

        # Move
        $x += $d                            
        $y += $e

        # "Replace" the charcter at the current position
        # PadRight() ensures the string is long enough          
        $s[ $y ]=$s[ $y ].PadRight( $x+1 ).Remove( $x, 1 ).Insert( $x, $c )
    } while( $d -or $e ) # Until the next dot is reached
}

# Print the resulting string array
$s