Add some standard comments and hash bang lines.

15 files changed, 143 insertions, 28 deletions

diff --git a/challenge-096/abigail/awk/ch-1.awk b/challenge-096/abigail/awk/ch-1.awk
index 744c154648..dae5328b5f 100644..100755
--- a/challenge-096/abigail/awk/ch-1.awk
+++ b/challenge-096/abigail/awk/ch-1.awk
@@ -1,3 +1,13 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-1.awk < input-file
+#
+
 #
 # AWK splits lines on whitespace, making each field available
 # in $1, $2, ..., etc. So, we just print the fields in reverse,
diff --git a/challenge-096/abigail/awk/ch-2.awk b/challenge-096/abigail/awk/ch-2.awk
index 08cebccb4e..9d3c9fb492 100644..100755
--- a/challenge-096/abigail/awk/ch-2.awk
+++ b/challenge-096/abigail/awk/ch-2.awk
@@ -1,3 +1,13 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-2.awk < input-file
+#
+
 #
 # Return the minimum of 3 values
 #
diff --git a/challenge-096/abigail/bash/ch-1.sh b/challenge-096/abigail/bash/ch-1.sh
index 9122fae4e0..f4d4de34cb 100644..100755
--- a/challenge-096/abigail/bash/ch-1.sh
+++ b/challenge-096/abigail/bash/ch-1.sh
@@ -1,3 +1,13 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-1.sh < input-file
+#
+
 #
 # Read in a line from STDIN, split it on whitespace,
 # put the result into an array 'words'
diff --git a/challenge-096/abigail/c/ch-1.c b/challenge-096/abigail/c/ch-1.c
index 22ebafd404..36ec37d5fb 100644
--- a/challenge-096/abigail/c/ch-1.c
+++ b/challenge-096/abigail/c/ch-1.c
@@ -1,3 +1,11 @@
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-1.o ch-1.c; ch-1.o < input-file
+ */
+
 # include <stdlib.h>
 # include <stdio.h>
 # include <string.h>
diff --git a/challenge-096/abigail/c/ch-2.c b/challenge-096/abigail/c/ch-2.c
index 73f35b1c0a..0c88bff827 100644
--- a/challenge-096/abigail/c/ch-2.c
+++ b/challenge-096/abigail/c/ch-2.c
@@ -1,3 +1,11 @@
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-2.o ch-2.c; ch-2.o < input-file
+ */
+
 # include <stdlib.h>
 # include <stdio.h>
 # include <string.h>
@@ -20,19 +28,6 @@ size_t min3 (size_t a, size_t b, size_t c) {
 size_t LevenshteinDistance (char * first,  size_t n,
                             char * second, size_t m) {
       
-    /*
-     * If 'first' is the shorter string, swap the two strings.
-     * This reduces the memory usage.
-     */
-    if (n < m) {
-        char * tmp = first;
-        size_t t   = n;
-        first  = second;
-        second = tmp;
-        n      = m;
-        m      = t;
-    }
-
     size_t ** distance;
     if ((distance = malloc ((n + 1) * sizeof (size_t *))) == NULL) {
         fprintf (stderr, "Out of memory\n");
@@ -54,7 +49,7 @@ size_t LevenshteinDistance (char * first,  size_t n,
             /*
              * We only need the previous row; freeing the memory of rows
              * we no longer need, reduces the memory usage from
-             * Theta (n * m) to O (min (n, m))
+             * Theta (n * m) to O (n + m)
              */
             free (distance [i - 1]);
         }
diff --git a/challenge-096/abigail/lua/ch-1.lua b/challenge-096/abigail/lua/ch-1.lua
index 9c4b1de913..7ff3b94814 100644..100755
--- a/challenge-096/abigail/lua/ch-1.lua
+++ b/challenge-096/abigail/lua/ch-1.lua
@@ -1,3 +1,13 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-1.lua < input-file
+--
+
 for line in io . lines () do
     --
     -- Extract words and put them into an array, in reverse.
diff --git a/challenge-096/abigail/lua/ch-2.lua b/challenge-096/abigail/lua/ch-2.lua
index 162f06eef0..ef1b039579 100644..100755
--- a/challenge-096/abigail/lua/ch-2.lua
+++ b/challenge-096/abigail/lua/ch-2.lua
@@ -1,3 +1,13 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua < input-file
+--
+
 --
 -- This is an implementation of the Wagner Fischer algorithm, which
 -- calculates the Levenshtein distance.
@@ -7,11 +17,6 @@
 function LevenshteinDistance (first, second)
     local n = first  : len ()
     local m = second : len ()
-    if n < m
-    then
-        first, second = second, first
-        n,     m      = m,      n
-    end
     distances = {}
     for i = 0, n do
         distances [i] = {}
@@ -37,7 +42,7 @@ function LevenshteinDistance (first, second)
         --
         -- We only need the previous row, so we can return the
         -- memory of rows before that. This reduces the memory
-        -- usage from O (n * m) to O (min (n, m))
+        -- usage from Theta (n * m) to O (n + m)
         --
         if i > 0
         then
diff --git a/challenge-096/abigail/node/ch-1.js b/challenge-096/abigail/node/ch-1.js
index b31524a686..16d4f3eada 100644..100755
--- a/challenge-096/abigail/node/ch-1.js
+++ b/challenge-096/abigail/node/ch-1.js
@@ -1,3 +1,13 @@
+#!/usr/local/bin/node
+
+//
+// See ../README.md
+//
+
+//
+// Run as: node ch-1.js < input-file
+//
+
 //
 // Read STDIN. Split on newlines, filter out empty lines, then call "main".
 //
diff --git a/challenge-096/abigail/node/ch-2.js b/challenge-096/abigail/node/ch-2.js
index 8423ab96b8..a9618414a3 100644..100755
--- a/challenge-096/abigail/node/ch-2.js
+++ b/challenge-096/abigail/node/ch-2.js
@@ -1,6 +1,13 @@
+#!/usr/local/bin/node
+
+//
+// See ../README.md
 //
-// Read STDIN. Split on newlines, filter out empty lines, then call "main".
+
 //
+// Run as: node ch-2.js < input-file
+//
+
   require      ("fs")
 . readFileSync (0)               // Read all.
 . toString     ()                // Turn it into a string.
diff --git a/challenge-096/abigail/perl/ch-1.pl b/challenge-096/abigail/perl/ch-1.pl
index ddca656054..ccd4146db5 100644..100755
--- a/challenge-096/abigail/perl/ch-1.pl
+++ b/challenge-096/abigail/perl/ch-1.pl
@@ -1,5 +1,13 @@
 #!/opt/perl/bin/perl
 
+#
+# See ../README.md
+#
+
+#
+# Run as: perl ch-1.pl < input-file
+#
+
 use 5.032;
 
 use strict;
diff --git a/challenge-096/abigail/perl/ch-2.pl b/challenge-096/abigail/perl/ch-2.pl
index bb58c84569..45aa08416b 100644..100755
--- a/challenge-096/abigail/perl/ch-2.pl
+++ b/challenge-096/abigail/perl/ch-2.pl
@@ -1,4 +1,12 @@
+#!/opt/perl/bin/perl
 
+#
+# See ../README.md
+#
+
+#
+# Run as: perl ch-2.pl < input-file
+#
 
 use 5.032;
 
@@ -18,8 +26,6 @@ use List::Util 'min';
 # See https://en.wikipedia.org/wiki/Wagner%E2%80%93Fischer_algorithm
 #
 sub LevenshteinDistance ($first, $second) {
-   ($first, $second) = ($second, $first) if length ($first) <
-                                            length ($second);
     my $distance;
     for (my $i = 0; $i <= length ($first); $i ++) {
         for (my $j = 0; $j <= length ($second); $j ++) {
@@ -33,7 +39,7 @@ sub LevenshteinDistance ($first, $second) {
         }
         #
         # We only need the previous row; this reduces the memory
-        # from O (N * M) to O (min (N, M)), where N and M are the
+        # from Theta (N * M) to O (N + M), where N and M are the
         # lengths of the input strings.
         #
         undef $$distance [$i - 1] if $i;
diff --git a/challenge-096/abigail/python/ch-1.py b/challenge-096/abigail/python/ch-1.py
index ddc34e2633..84a1c2618b 100644..100755
--- a/challenge-096/abigail/python/ch-1.py
+++ b/challenge-096/abigail/python/ch-1.py
@@ -1,3 +1,13 @@
+#!/opt/local/bin/python
+
+#
+# See ../README.md
+#
+
+#
+# Run as: python ch-1.py < input-file
+#
+
 import fileinput
 
 for line in fileinput . input ():
diff --git a/challenge-096/abigail/python/ch-2.py b/challenge-096/abigail/python/ch-2.py
index deaeff14cf..2e24e442f8 100644..100755
--- a/challenge-096/abigail/python/ch-2.py
+++ b/challenge-096/abigail/python/ch-2.py
@@ -1,3 +1,13 @@
+#!/opt/local/bin/python
+
+#
+# See ../README.md
+#
+
+#
+# Run as: python ch-2.py < input-file
+#
+
 import fileinput
 
 def LevenshteinDistance (first, second):
diff --git a/challenge-096/abigail/ruby/ch-1.rb b/challenge-096/abigail/ruby/ch-1.rb
index 064f780345..9bef80402c 100644..100755
--- a/challenge-096/abigail/ruby/ch-1.rb
+++ b/challenge-096/abigail/ruby/ch-1.rb
@@ -1,3 +1,13 @@
+#!/usr/bin/ruby
+
+#
+# See ../README.md
+#
+
+#
+# Run as: ruby ch-1.rb < input-file
+#
+
 ARGF . each_line do |_|
     puts ((_ . split (/\s+/)) . grep (/\S/)) . reverse . join (" ")
 end
diff --git a/challenge-096/abigail/ruby/ch-2.rb b/challenge-096/abigail/ruby/ch-2.rb
index 65a57bd6d3..931de4f2d7 100644..100755
--- a/challenge-096/abigail/ruby/ch-2.rb
+++ b/challenge-096/abigail/ruby/ch-2.rb
@@ -1,10 +1,16 @@
+#!/usr/bin/ruby
+
+#
+# See ../README.md
+#
+
+#
+# Run as: ruby ch-2.rb < input-file
+#
+
 def LevenshteinDistance (first, second)
     n = first  . length
     m = second . length
-    if n < m
-        first, second = second, first
-        n,     m      = m,      n
-    end
     distances = []
     for i in 0 .. n do
         distances [i] = []