Code Golf: Connecting the dots

Answer 1

C#, 422 chars

758 754 641 627 584 546 532 486 457 454 443 440 422 chars (next time maybe I won't submit so soon.)

using A=System.Console;class B{static int C,o,d,e,G,O=1,f,F,u,n;static 
void Main(){var s=A.In.ReadToEnd();A.Clear();while(++u32){if(int.Parse(s[u]+""+s[++u])==O){o=
e>f?1:f>e?-1:0;C=d>F?1:F>d?-1:0 ;G=e+o;n=d+C;if(O++>1)while(n!=F||G!=f)
{A.SetCursorPosition(G-=o,n-=C);A.Write( "+/-|\\"[n==d&&G==e?0:n==F&&G
==f?0:C+o==0?1:C==0?2:o==0?3:4]);}e=f;d=F;F=0;f=u=-1 ;}f++;}}A.Read();}}

Usage: run, paste (or type) the input, ensure the last line is terminated, press CTRL-Z or F6, press Enter.

Formatted but still basically unintelligable version:

using A = System.Console;
class B
{
    // code golf fun!
    static int C, o, d, e, G, O = 1, f, F, u, n;
    static void Main()
    {
        // read the input into a string char by char until EOF
        var s = A.In.ReadToEnd();
      
        A.Clear(); // clear console, ready to draw picture

        // O is the "dot" number we're looking for 
        // f is current column 
        // F is current row
        // loop over the field looking for numbers sequentially 
        // until no more are found
        while (++u < s.Length)
        {
            f++;
            // any char <32 is expected to be a CR/LF 
            // increment the current row and reset the current column
            if (s[u] < 32)
            {
                u++; // skip the other half of the CR/LF pair
                F++; // next row
                f = 0; // column reset
            }
            // any char >32 is expected to be a number
            if (s[u] > 32)
            {
                // parse the current + next char and see if it's 
                // the number we want
                if (int.Parse(s[u] + "" + s[++u]) == O)
                {
                    // set up coordinates, compare X1 with X2 
                    // and Y1 with Y2 to figure out line direction
                    
                    // horizontal direction (same as o=e.CompareTo(f))
                    o = e > f ? 1 : f > e ? - 1 : 0; 

                    // vertical direction (same as C=d.CompareTo(F))
                    C = d > F ? 1 : F > d ? - 1 : 0; 

                    // initial offsets compensate for off-by-one
                    G = e + o;
                    n = d + C;

                    // draw the line (except for the very first dot) 
                    if (O++ > 1)
                        while (n != F || G != f)
                        {
                            // update coords and write desired char 
                            A.SetCursorPosition(G -= o, n -= C);

                            // this lovely line decides which char to 
                            // print, and prints it
                            A.Write(
                               "+/-|\\"[n == d && G == e ? 0 : n == F && G 
                               == f ? 0 : C + o == 0 ? 1 : C == 0 ? 2 : o 
                               == 0 ? 3 : 4]);
                        }

                    // remember end point of this line, to use as start point 
                    // of next line
                    e = f;
                    d = F;

                    // reset current row (F), column (f), field position (u)
                    F = 0;
                    f = u = -1;
                }
           
                // bump current column because we parse 2 chars when we 
                // find a dot                
                f++;                 
            }
        }
        A.Read(); // prevent command prompt from overwriting picture
    }
}