Week 151: Make the algorithm for part 2 even simpler.

No need for an additional array: add two 0's to the array of
valuables, and modify in situ.

7 files changed, 44 insertions, 66 deletions

diff --git a/challenge-151/abigail/awk/ch-2.awk b/challenge-151/abigail/awk/ch-2.awk
index 65428f81e8..732444708f 100644
--- a/challenge-151/abigail/awk/ch-2.awk
+++ b/challenge-151/abigail/awk/ch-2.awk
@@ -13,12 +13,9 @@ function max (a, b) {
 }
 
 {
-    delete best
-    best [NF + 1] = 0
-    best [NF + 2] = 0
     for (i = NF; i > 2; i --) {
-        best [i] = max($i + best [i + 2], best [i + 1])
+        $i = max($i + $(i + 2), $(i + 1))
     }
-    print $1 + best [3]
+    print $1 + $3
 }
 
diff --git a/challenge-151/abigail/bash/ch-2.sh b/challenge-151/abigail/bash/ch-2.sh
index 6a9eceec29..cb009e0e16 100644
--- a/challenge-151/abigail/bash/ch-2.sh
+++ b/challenge-151/abigail/bash/ch-2.sh
@@ -10,17 +10,14 @@
 
 set -f
 
-declare -a best
-
-while read -a houses
-do    size=${#houses[@]}
-      best[$((size + 0))]=0
-      best[$((size + 1))]=0
-      for  ((i = size - 1; i >= 2; i --))
-      do   ((val1 = ${houses[$i]} + ${best[$((i + 2))]}))
-           ((val2 = ${best[$((i + 1))]}))
-           best[$i]=$((val1 < val2 ? val2 : val1))
+while read -a h
+do    h[${#h[@]}]=0
+      h[${#h[@]}]=0
+      for  ((i = ${#h[@]} - 3; i >= 2; i --))
+      do   ((val1 = ${h[$i]} + ${h[$((i + 2))]}))
+           ((val2 = ${h[$((i + 1))]}))
+           h[$i]=$((val1 < val2 ? val2 : val1))
       done
 
-      echo $((${houses[0]} + ${best[2]}))
+      echo $((${h[0]} + ${h[2]}))
 done
diff --git a/challenge-151/abigail/c/ch-2.c b/challenge-151/abigail/c/ch-2.c
index 34e7e24ac1..9c46968f80 100644
--- a/challenge-151/abigail/c/ch-2.c
+++ b/challenge-151/abigail/c/ch-2.c
@@ -21,39 +21,30 @@ int main (void) {
 
     while ((str_len = getline (&line, &len, stdin)) != -1) {
         char * line_ptr = line;
-        int * houses = NULL;
-        int * best   = NULL;
+        int * h = NULL;
         int val;
         int offset;
-        int nr_of_houses = 0;
+        int sz = 0;
 
         while (sscanf (line_ptr, "%d%n", &val, &offset) == 1) {
-            if ((houses = (int *)
-                 realloc (houses, ++ nr_of_houses * sizeof (int))) == NULL) {
+            if ((h = (int *) realloc (h, (2 + ++ sz) * sizeof (int))) == NULL) {
                 perror ("Recalloc failed");
                 exit (1);
             }
-            houses [nr_of_houses - 1] = val;
+            h [sz - 1] = val;
             line_ptr += offset;
         }
 
-        if ((best = (int *)
-             malloc ((nr_of_houses + 2) * sizeof (int))) == NULL) {
-            perror ("Malloc failed");
-            exit (1);
-        }
-
-        best [nr_of_houses + 0] = 0;
-        best [nr_of_houses + 1] = 0;
+        h [sz + 0] = 0;
+        h [sz + 1] = 0;
 
-        for (int i = nr_of_houses - 1; i >= 2; i --) {
-            best [i] = max (houses [i] + best [i + 2], best [i + 1]);
+        for (int i = sz - 1; i >= 2; i --) {
+            h [i] = max (h [i] + h [i + 2], h [i + 1]);
         }
 
-        printf ("%d\n", houses [0] + best [2]);
+        printf ("%d\n", h [0] + h [2]);
 
-        free (houses);
-        free (best);
+        free (h);
     }
     free (line);
 
diff --git a/challenge-151/abigail/lua/ch-2.lua b/challenge-151/abigail/lua/ch-2.lua
index 0e644d0a6c..d8ac15c101 100644
--- a/challenge-151/abigail/lua/ch-2.lua
+++ b/challenge-151/abigail/lua/ch-2.lua
@@ -9,18 +9,17 @@
 --
 
 for line in io . lines () do
-    local houses = {}
-    local best   = {}
+    local h = {}
     for val in line : gmatch ("%d+") do
-        houses [#houses + 1] = val
+        h [#h + 1] = val
     end
 
-    best [#houses + 1] = 0
-    best [#houses + 2] = 0
+    h [#h + 1] = 0
+    h [#h + 1] = 0
 
-    for i = #houses, 3, -1 do
-        best [i] = math . max (houses [i] + best [i + 2], best [i + 1])
+    for i = #h - 2, 3, -1 do
+        h [i] = math . max (h [i] + h [i + 2], h [i + 1])
     end
 
-    print (houses [1] + best [3])
+    print (h [1] + h [3])
 end
diff --git a/challenge-151/abigail/node/ch-2.js b/challenge-151/abigail/node/ch-2.js
index 079c61e0ce..11a88c6bc7 100644
--- a/challenge-151/abigail/node/ch-2.js
+++ b/challenge-151/abigail/node/ch-2.js
@@ -11,13 +11,11 @@
   require ('readline')
 . createInterface ({input: process . stdin})   
 . on              ('line', line => {
-    let houses = line . trim () . split (/ +/) . map (n => +n)
-    let best   = []
-    let size   = houses . length
-    best [size + 0] = 0
-    best [size + 1] = 0
-    for (let i = size - 1; i >= 2; i --) {
-        best [i] = Math . max (houses [i] + best [i + 2], best [i + 1])
+    let h = line . trim () . split (/ +/) . map (n => +n)
+    h [h . length] = 0
+    h [h . length] = 0
+    for (let i = h . length - 3; i >= 2; i --) {
+        h [i] = Math . max (h [i] + h [i + 2], h [i + 1])
     }
-    console . log (houses [0] + best [2])
+    console . log (h [0] + h [2])
 })
diff --git a/challenge-151/abigail/perl/ch-2.pl b/challenge-151/abigail/perl/ch-2.pl
index 9c1e1d3b60..df731f4cfe 100644
--- a/challenge-151/abigail/perl/ch-2.pl
+++ b/challenge-151/abigail/perl/ch-2.pl
@@ -34,15 +34,10 @@ use List::Util qw [max];
 # And we must always pick the first house.
 #
 
-sub best ($houses) {
-    my @best;
-    $best [$#$houses + 1] = 0;
-    $best [$#$houses + 2] = 0;
-    for (my $i = $#$houses; $i >= 2; $i --) {
-        $best [$i] = max $$houses [$i] + $best [$i + 2], $best [$i + 1];
-    }
-    $$houses [0] + $best [2];
+while (<>) {
+    my @h = (/[0-9]+/g, 0, 0);
+    $h [$_] = max $h [$_] + $h [$_ + 2], $h [$_ + 1] for reverse 2 .. $#h - 2;
+    say $h [0] + $h [2];
 }
 
-
-say best [/[0-9]+/g] while <>;
+__END__
diff --git a/challenge-151/abigail/python/ch-2.py b/challenge-151/abigail/python/ch-2.py
index a20a18329b..52522eff0b 100644
--- a/challenge-151/abigail/python/ch-2.py
+++ b/challenge-151/abigail/python/ch-2.py
@@ -11,8 +11,9 @@
 import fileinput
 
 for line in fileinput . input ():
-    houses = list (map (lambda x: int (x), line . strip () . split ()))
-    best   = [0] * (len (houses) + 2)
-    for i in range (len (houses) - 1, 1, -1):
-        best [i] = max (houses [i] + best [i + 2], best [i + 1])
-    print (houses [0] + best [2])
+    h = list (map (lambda x: int (x), line . strip () . split ()))
+    h . append (0)
+    h . append (0)
+    for i in range (len (h) - 3, 1, -1):
+        h [i] = max (h [i] + h [i + 2], h [i + 1])
+    print (h [0] + h [2])