Merge pull request #5913 from Firedrake/rogerbw-challenge-160

Solutions for challenge #160

18 files changed, 946 insertions, 0 deletions

diff --git a/challenge-160/roger-bell-west/javascript/ch-1.js b/challenge-160/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..18097af7c5
--- /dev/null
+++ b/challenge-160/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,51 @@
+#! /usr/bin/node
+
+function fim (n0) {
+    let words=["zero","one","two","three","four",
+               "five","six","seven","eight","nine"]
+    let n=n0
+    let p=[]
+    while (true) {
+        let s=words[n] + " is "
+        if (n == 4) {
+            s += "magic."
+            p.push(s)
+            break
+        } else {
+            n=words[n].length
+            s += words[n]
+            p.push(s)
+        }
+    }
+    return p.join(", ").replace(/^\w/,function (c) {
+        return c.toUpperCase()
+    })
+}
+
+if (fim(5) == "Five is four, four is magic.") {
+    process.stdout.write("Pass")
+} else {
+    process.stdout.write("FAIL")
+}
+process.stdout.write(" ");
+
+if (fim(7) == "Seven is five, five is four, four is magic.") {
+    process.stdout.write("Pass")
+} else {
+    process.stdout.write("FAIL")
+}
+process.stdout.write(" ");
+
+if (fim(6) == "Six is three, three is five, five is four, four is magic.") {
+    process.stdout.write("Pass")
+} else {
+    process.stdout.write("FAIL")
+}
+process.stdout.write(" ");
+
+if (fim(4) == "Four is magic.") {
+    process.stdout.write("Pass")
+} else {
+    process.stdout.write("FAIL")
+}
+process.stdout.write("\n");
diff --git a/challenge-160/roger-bell-west/javascript/ch-2.js b/challenge-160/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..40ad5412b6
--- /dev/null
+++ b/challenge-160/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,35 @@
+#! /usr/bin/node
+
+function equilibriumindex (s) {
+    let sm=s.reduce((x,y) => x+y, 0)
+    let sa=0
+    for (let [i,v] of s.entries()) {
+        sa += v
+        if (sa == sm) {
+            return i
+        }
+        sa += v
+    }
+    return -1
+}
+
+if (equilibriumindex([1,3,5,7,9]) == 3) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+
+if (equilibriumindex([1,2,3,4,5]) == -1) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+
+if (equilibriumindex([2,4,2]) == 1) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-160/roger-bell-west/kotlin/ch-1.kt b/challenge-160/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..c7964f46d0
--- /dev/null
+++ b/challenge-160/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,48 @@
+import kotlin.math.*
+
+fun fim(n0: Int): String {
+    val words=listOf("zero","one","two","three","four",
+                     "five","six","seven","eight","nine")
+    var n=n0
+    var p=ArrayList<String>()
+    while (true) {
+        var s = words[n] + " is "
+        if (n == 4) {
+            s += "magic."
+            p.add(s)
+            break
+        } else {
+            n = words[n].length
+            s += words[n]
+            p.add(s)
+        }
+    }
+    return p.joinToString(", ").replaceFirstChar(Char::titlecase)
+}
+
+fun main() {
+    if (fim(5) == "Five is four, four is magic.") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (fim(7) == "Seven is five, five is four, four is magic.") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (fim(6) == "Six is three, three is five, five is four, four is magic.") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (fim(4) == "Four is magic.") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-160/roger-bell-west/kotlin/ch-2.kt b/challenge-160/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..34ed8e2667
--- /dev/null
+++ b/challenge-160/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,35 @@
+import kotlin.math.*
+
+fun equilibriumindex(s: List<Int>): Int {
+    val sm = s.sum()
+    var sa = 0
+    for ((i,v) in s.withIndex()) {
+        sa += v
+        if (sa == sm) {
+            return i
+        }
+        sa += v
+    }
+    return -1
+}
+
+fun main() {
+    if (equilibriumindex(listOf(1,3,5,7,9)) == 3) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (equilibriumindex(listOf(1,2,3,4,5)) == -1) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (equilibriumindex(listOf(2,4,2)) == 1) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-160/roger-bell-west/lua/ch-1.lua b/challenge-160/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..4c73ccc235
--- /dev/null
+++ b/challenge-160/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,49 @@
+#! /usr/bin/lua
+
+function fim(n0)
+   words={"zero","one","two","three","four",
+          "five","six","seven","eight","nine"}
+   local n=n0
+   local p={}
+   while true do
+      local s=words[n+1] .. " is "
+      if n==4 then
+         s = s .. "magic."
+         table.insert(p,s)
+         break
+      else
+         n = #(words[n+1])
+         s = s .. words[n+1]
+         table.insert(p,s)
+      end
+   end
+   return string.gsub(table.concat(p,", "),"^(%a)",string.upper)
+end
+
+if fim(5) == "Five is four, four is magic." then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if fim(7) == "Seven is five, five is four, four is magic." then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if fim(6) == "Six is three, three is five, five is four, four is magic." then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if fim(4) == "Four is magic." then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-160/roger-bell-west/lua/ch-2.lua b/challenge-160/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..00611ad38d
--- /dev/null
+++ b/challenge-160/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,38 @@
+#! /usr/bin/lua
+
+function equilibriumindex(s)
+   local sm=0
+   for k,v in ipairs(s) do
+      sm = sm + v
+   end
+   local sa=0
+   for k,v in ipairs(s) do
+      sa = sa + v
+      if sa == sm then
+         return k
+      end
+      sa = sa + v
+   end
+   return 0
+end
+
+if equilibriumindex({1,3,5,7,9}) == 4 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if equilibriumindex({1,2,3,4,5}) == 0 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if equilibriumindex({2,4,2}) == 2 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-160/roger-bell-west/perl/ch-1.pl b/challenge-160/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..f945c0965e
--- /dev/null
+++ b/challenge-160/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,30 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 4;
+
+is(fim(5),"Five is four, four is magic.",'example 1');
+is(fim(7),"Seven is five, five is four, four is magic.",'example 2');
+is(fim(6),"Six is three, three is five, five is four, four is magic.",'example 3');
+is(fim(4),"Four is magic.",'example 4');
+
+sub fim {
+  my $n=shift;
+  my @words=qw(zero one two three four five six seven eight nine);
+  my @p;
+  while (1) {
+    my $s=$words[$n] . ' is ';
+    if ($n == 4) {
+      $s .= 'magic.';
+      push @p,$s;
+      last;
+    } else {
+      $n=length($words[$n]);
+      $s .= $words[$n];
+      push @p,$s;
+    }
+  }
+  return ucfirst(join(', ',@p));
+}
diff --git a/challenge-160/roger-bell-west/perl/ch-2.pl b/challenge-160/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..b5315ad1f7
--- /dev/null
+++ b/challenge-160/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,25 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 3;
+use List::Util qw(sum);
+
+is(equilibriumindex([1,3,5,7,9]),3,'example 1');
+is(equilibriumindex([1,2,3,4,5]),-1,'example 2');
+is(equilibriumindex([2,4,2]),1,'example 3');
+
+sub equilibriumindex {
+  my $s=shift;
+  my $sm=sum(@{$s});
+  my $sa=0;
+  foreach my $i (0..$#{$s}) {
+    $sa += $s->[$i];
+    if ($sa == $sm) {
+      return $i;
+    }
+    $sa += $s->[$i];
+  }
+  return -1;
+}
diff --git a/challenge-160/roger-bell-west/postscript/ch-1.ps b/challenge-160/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..78445003b6
--- /dev/null
+++ b/challenge-160/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,169 @@
+%!PS
+
+% begin library code
+
+/strconcat % (a) (b) -> (ab)  
+{ exch dup length
+  2 index length add string
+  dup dup 4 2 roll copy length
+  4 -1 roll putinterval
+} bind def
+
+/strjoin % [(a) (b) (c)] (j) -> (ajbjc)
+{
+    3 dict begin
+    /j exch def
+    dup 0 get /out exch def
+    /first true def
+    {
+        first {
+            /first false def
+        } {
+            out j strconcat
+            exch strconcat
+            /out exch def
+        } ifelse
+    } forall
+    out
+    end
+} def
+
+/apush { % [a b] c -> [a b c]
+    exch
+    [ exch aload length 2 add -1 roll ]
+} bind def
+
+/deepeq {
+    2 dict begin
+    /a exch def
+    /b exch def
+    a type b type eq {
+        a type /dicttype eq {
+            a length b length eq {
+                <<
+                    a {
+                        pop
+                        true
+                    } forall
+                    b {
+                        pop
+                        true
+                    } forall
+                >>
+                true exch
+                {
+                    pop
+                    dup a exch known {
+                        dup b exch known {
+                            dup a exch get exch b exch get deepeq not {
+                                pop false
+                            } if
+                        } {
+                            false
+                        } ifelse
+                    } {
+                        false
+                    } ifelse
+                } forall
+            } {
+                false
+            } ifelse
+        } {
+            a type dup /arraytype eq exch /stringtype eq or {
+                a length b length eq {
+                    true
+                    0 1 a length 1 sub {
+                        dup a exch get exch b exch get deepeq not {
+                            pop false
+                            exit
+                        } if
+                    } for
+                } {
+                    false
+                } ifelse
+            } {
+                a b eq
+            } ifelse
+        } ifelse
+    } {
+        false
+    } ifelse
+    end
+} bind def
+
+/test {
+    /test.count test.count 1 add def
+    {
+        /test.pass test.pass 1 add def
+    } {
+        ( ) print
+        test.count (....) cvs print
+        (-fail) print
+    } ifelse
+} bind def
+
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/test.end {
+    ( ) print
+    test.count 0 gt {
+        (Passed ) print
+        test.pass (...) cvs print
+        (/) print
+        test.count (...) cvs print
+        ( \() print
+        test.pass 100 mul test.count idiv (...) cvs print
+        (%\)) print
+        (\r\n) print
+    } if
+} bind def
+
+% end library code
+
+/fid {
+    3 dict begin
+    /words [ (zero) (one) (two) (three) (four)
+             (five) (six) (seven) (eight) (nine) ] def
+    /p 0 array def
+        {
+            dup
+            words exch get ( is ) strconcat /s exch def
+            dup 4 eq {
+                pop
+                /s s (magic.) strconcat def
+                /p p s apush def
+                exit
+            } {
+                words exch get length
+                dup words exch get s exch strconcat /s exch def
+                /p p s apush def
+            } ifelse
+        } loop
+    p (, ) strjoin
+    dup 0 get 32 sub exch dup 3 -1 roll 0 exch put
+    end
+} bind def
+
+(fid) test.start
+
+5 fid
+(Five is four, four is magic.)
+deepeq test
+
+7 fid
+(Seven is five, five is four, four is magic.)
+deepeq test
+
+6 fid
+(Six is three, three is five, five is four, four is magic.)
+deepeq test
+
+4 fid
+(Four is magic.)
+deepeq test
+
+test.end
diff --git a/challenge-160/roger-bell-west/postscript/ch-2.ps b/challenge-160/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..14ba76e597
--- /dev/null
+++ b/challenge-160/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,84 @@
+%!PS
+
+% begin library code
+
+/test {
+    /test.count test.count 1 add def
+    {
+        /test.pass test.pass 1 add def
+    } {
+        ( ) print
+        test.count (....) cvs print
+        (-fail) print
+    } ifelse
+} bind def
+
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} bind def
+
+/test.end {
+    ( ) print
+    test.count 0 gt {
+        (Passed ) print
+        test.pass (...) cvs print
+        (/) print
+        test.count (...) cvs print
+        ( \() print
+        test.pass 100 mul test.count idiv (...) cvs print
+        (%\)) print
+        (\r\n) print
+    } if
+} bind def
+
+/reduce { % array proc -> value
+    2 dict begin
+    /p exch def
+    /a exch def
+    a 0 get
+    1 1 a length 1 sub {
+        a exch get
+        p
+    } for
+    end
+} bind def
+
+/enumerate.array {
+    1 dict begin
+    /a exch def
+    [
+      0 1 a length 1 sub {
+          [ exch dup a exch get ]
+      } for
+    ]
+    end
+} bind def
+
+% end library code
+
+/equilibriumindex {
+    3 dict begin
+    /x -1 def
+    dup { add } reduce /sm exch def
+    /sa 0 def
+    enumerate.array {
+        dup 1 get sa add /sa exch def
+        sa sm eq {
+            0 get /x exch def
+            exit
+        } if
+        1 get sa add /sa exch def
+    } forall
+    x
+    end
+} bind def
+
+(equilibriumindex) test.start
+
+[ 1 3 5 7 9 ] equilibriumindex 3 eq test
+[ 1 2 3 4 5 ] equilibriumindex -1 eq test
+[ 2 4 2 ] equilibriumindex 1 eq test
+
+test.end
diff --git a/challenge-160/roger-bell-west/python/ch-1.py b/challenge-160/roger-bell-west/python/ch-1.py
new file mode 100755
index 0000000000..3881cbf52f
--- /dev/null
+++ b/challenge-160/roger-bell-west/python/ch-1.py
@@ -0,0 +1,44 @@
+#! /usr/bin/python3
+
+import unittest
+
+def fim(n0):
+  words=["zero","one","two","three","four",
+         "five","six","seven","eight","nine"]
+  n=n0
+  p=[]
+  while True:
+    s = words[n] + " is "
+    if n==4:
+      s += "magic."
+      p.append(s)
+      break
+    else:
+      n = len(words[n])
+      s += words[n]
+      p.append(s)
+  return (", ".join(p)).capitalize()
+
+class TestFim(unittest.TestCase):
+
+        def test_ex1(self):
+          self.assertEqual(fim(5),
+                           "Five is four, four is magic.",
+                           'example 1')
+
+        def test_ex2(self):
+          self.assertEqual(fim(7),
+                           "Seven is five, five is four, four is magic.",
+                           'example 2')
+
+        def test_ex3(self):
+          self.assertEqual(fim(6),
+                           "Six is three, three is five, five is four, four is magic.",
+                           'example 3')
+
+        def test_ex4(self):
+          self.assertEqual(fim(4),
+                           "Four is magic.",
+                           'example 4')
+
+unittest.main()
diff --git a/challenge-160/roger-bell-west/python/ch-2.py b/challenge-160/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..aeca8ffbb1
--- /dev/null
+++ b/challenge-160/roger-bell-west/python/ch-2.py
@@ -0,0 +1,34 @@
+#! /usr/bin/python3
+
+import unittest
+
+from functools import reduce
+
+def equilibriumindex(s):
+  sm=sum(s)
+  sa=0
+  for i,v in enumerate(s):
+    sa += v
+    if sa == sm:
+      return i
+    sa += v
+  return -1
+
+class TestEquilibriumindex(unittest.TestCase):
+
+        def test_ex1(self):
+          self.assertEqual(equilibriumindex([1,3,5,7,9]),
+                           3,
+                           'example 1')
+
+        def test_ex2(self):
+          self.assertEqual(equilibriumindex([1,2,3,4,5]),
+                           -1,
+                           'example 2')
+
+        def test_ex3(self):
+          self.assertEqual(equilibriumindex([2,4,2]),
+                           1,
+                           'example 3')
+
+unittest.main()
diff --git a/challenge-160/roger-bell-west/raku/ch-1.p6 b/challenge-160/roger-bell-west/raku/ch-1.p6
new file mode 100755
index 0000000000..d4c1a17dbe
--- /dev/null
+++ b/challenge-160/roger-bell-west/raku/ch-1.p6
@@ -0,0 +1,30 @@
+#! /usr/bin/perl6
+
+use Test;
+
+plan 4;
+
+is(fim(5),"Five is four, four is magic.",'example 1');
+is(fim(7),"Seven is five, five is four, four is magic.",'example 2');
+is(fim(6),"Six is three, three is five, five is four, four is magic.",'example 3');
+is(fim(4),"Four is magic.",'example 4');
+
+sub fim($n0) {
+    my $n=$n0;
+    my @words=("zero","one","two","three","four",
+               "five","six","seven","eight","nine");
+    my @p;
+    while (True) {
+        my $s=@words[$n] ~ ' is ';
+        if ($n==4) {
+            $s ~= 'magic.';
+            @p.push($s);
+            last;
+        } else {
+            $n=chars(@words[$n]);
+            $s ~= @words[$n];
+            @p.push($s);
+        }
+    }
+    return tc(join(', ',@p));
+}
diff --git a/challenge-160/roger-bell-west/raku/ch-2.p6 b/challenge-160/roger-bell-west/raku/ch-2.p6
new file mode 100755
index 0000000000..dc797f081e
--- /dev/null
+++ b/challenge-160/roger-bell-west/raku/ch-2.p6
@@ -0,0 +1,89 @@
+#! /usr/bin/perl6
+
+use Test;
+
+plan 3;
+
+is(equilibriumindex([1,3,5,7,9]),3,'example 1');
+
+is(equilibriumindex([1,2,3,4,5]),-1,'example 2');
+
+is(equilibriumindex([2,4,2]),1,'example 3');
+
+sub equilibriumindex(@s) {
+    my $sm=sum(@s);
+    my $sa=0;
+    for @s.kv -> $i,$v {
+        $sa += $v;
+        if ($sa == $sm) {
+            return $i;
+        }
+        $sa += $v;
+    }
+    return -1;
+}
+
+sub genprimes($mx) {
+    my @primes;
+    {
+        my $primesh=(2,3).SetHash;
+        loop (my $i=6;$i <= $mx+1; $i += 6) {
+            for ($i-1,$i+1) -> $j {
+                if ($j <= $mx) {
+                    $primesh{$j}=True;
+                }
+            }
+        }
+        my $p=2;
+        my @q=[2,3,5,7];
+        my $mr=floor(sqrt($mx));
+        while ($p <= $mr) {
+            if ($primesh{$p}:exists) {
+                my $i=$p*$p;
+                while ($i <= $mx) {
+                    $primesh{$i}:delete;
+                    $i += $p;
+                }
+            }
+            if (@q.elems < 2) {
+                @q.push(@q[*-1]+4);
+                @q.push(@q[*-1]+2);
+            }
+            $p=@q.shift;
+        }
+        @primes=$primesh.keys.sort;
+    }
+    return @primes;
+}
+
+sub primefactor($n) {
+    my %f;
+    my $m=$n;
+    for genprimes(floor(sqrt($n))) -> $p {
+        while ($m % $p == 0) {
+            %f{$p}++;
+            $m=floor($m/$p);
+        }
+        if ($m == 1) {
+            last;
+        }
+    }
+    if ($m > 1) {
+        %f{$m}++;
+    }
+    return %f;
+} 
+
+sub moebius($n) {
+    my $z=0;
+    for primefactor($n).values -> $v {
+        if ($v > 1) {
+            return 0;
+        }
+        $z++;
+    }
+    if ($z % 2 == 0) {
+        return 1;
+    }
+    return -1;
+}
diff --git a/challenge-160/roger-bell-west/ruby/ch-1.rb b/challenge-160/roger-bell-west/ruby/ch-1.rb
new file mode 100755
index 0000000000..a490156938
--- /dev/null
+++ b/challenge-160/roger-bell-west/ruby/ch-1.rb
@@ -0,0 +1,47 @@
+#! /usr/bin/ruby
+
+require 'test/unit'
+
+def fim(n0)
+  words=["zero","one","two","three","four",
+         "five","six","seven","eight","nine"]
+  n=n0
+  p=[]
+  while true do
+    s = words[n] + " is "
+    if n==4 then
+      s += "magic."
+      p.push(s)
+      break
+    else
+      n = words[n].length
+      s += words[n]
+      p.push(s)
+    end
+  end
+  return p.join(", ").capitalize
+end
+
+class TestFim < Test::Unit::TestCase
+
+  def test_ex1
+    assert_equal("Five is four, four is magic.",
+                 fim(5))
+  end
+
+  def test_ex2
+    assert_equal("Seven is five, five is four, four is magic.",
+                 fim(7))
+  end
+
+  def test_ex3
+    assert_equal("Six is three, three is five, five is four, four is magic.",
+                 fim(6))
+  end
+
+  def test_ex4
+    assert_equal("Four is magic.",
+                 fim(4))
+  end
+
+end
diff --git a/challenge-160/roger-bell-west/ruby/ch-2.rb b/challenge-160/roger-bell-west/ruby/ch-2.rb
new file mode 100755
index 0000000000..eb1ce62389
--- /dev/null
+++ b/challenge-160/roger-bell-west/ruby/ch-2.rb
@@ -0,0 +1,35 @@
+#! /usr/bin/ruby
+
+require 'test/unit'
+
+def equilibriumindex(s)
+  sm=s.sum
+  sa=0
+  s.each_with_index do |v,i|
+    sa += v
+    if sa == sm then
+      return i
+    end
+    sa += v
+  end
+  return -1
+end
+
+class TestEquilibriumindex < Test::Unit::TestCase
+
+  def test_ex1
+    assert_equal(3,
+                 equilibriumindex([1,3,5,7,9]))
+  end
+
+  def test_ex2
+    assert_equal(-1,
+                 equilibriumindex([1,2,3,4,5]))
+  end
+
+  def test_ex3
+    assert_equal(1,
+                 equilibriumindex([2,4,2]))
+  end
+
+end
diff --git a/challenge-160/roger-bell-west/rust/ch-1.rs b/challenge-160/roger-bell-west/rust/ch-1.rs
new file mode 100755
index 0000000000..aed6fa49c8
--- /dev/null
+++ b/challenge-160/roger-bell-west/rust/ch-1.rs
@@ -0,0 +1,64 @@
+#! /bin/sh
+//usr/bin/env rustc --test $0 -o ${0}x && ./${0}x --nocapture; rm -f ${0}x ; exit
+
+#[test]
+fn test_ex1() {
+    assert_eq!(
+        fim(5),
+        "Five is four, four is magic."
+    );
+}
+
+#[test]
+fn test_ex2() {
+    assert_eq!(
+        fim(7),
+        "Seven is five, five is four, four is magic."
+    );
+}
+
+#[test]
+fn test_ex3() {
+    assert_eq!(
+        fim(6),
+        "Six is three, three is five, five is four, four is magic."
+    );
+}
+
+#[test]
+fn test_ex4() {
+    assert_eq!(
+        fim(4),
+        "Four is magic."
+    );
+}
+
+fn fim(n0: usize) -> String {
+    let words=vec!["zero","one","two","three","four",
+                   "five","six","seven","eight","nine"];
+    let mut n = n0;
+    let mut p = Vec::new();
+    loop {
+        let mut s = format!("{} is ",words[n]);
+        if n==4 {
+            s.push_str("magic.");
+            p.push(s);
+            break;
+        } else {
+            n = words[n].len();
+            s.push_str(words[n]);
+            p.push(s);
+        }
+    }
+    upfirst(p.join(", "))
+}
+
+// borrowed from Shepmaster
+// https://stackoverflow.com/questions/38406793/why-is-capitalizing-the-first-letter-of-a-string-so-convoluted-in-rust
+fn upfirst(s: String) -> String {
+    let mut c = s.chars();
+    match c.next() {
+        None => String::new(),
+        Some(f) => f.to_uppercase().collect::<String>() + c.as_str(),
+    }
+}
diff --git a/challenge-160/roger-bell-west/rust/ch-2.rs b/challenge-160/roger-bell-west/rust/ch-2.rs
new file mode 100755
index 0000000000..c5bbc6d4dd
--- /dev/null
+++ b/challenge-160/roger-bell-west/rust/ch-2.rs
@@ -0,0 +1,39 @@
+#! /bin/sh
+//usr/bin/env rustc --test $0 -o ${0}x && ./${0}x --nocapture; rm -f ${0}x ; exit
+
+#[test]
+fn test_ex1() {
+    assert_eq!(
+        equilibriumindex(vec![1,3,5,7,9]),
+        3
+    );
+}
+
+#[test]
+fn test_ex2() {
+    assert_eq!(
+        equilibriumindex(vec![1,2,3,4,5]),
+        -1
+    );
+}
+
+#[test]
+fn test_ex3() {
+    assert_eq!(
+        equilibriumindex(vec![2,4,2]),
+        1
+    );
+}
+
+fn equilibriumindex(s: Vec<isize>) -> isize {
+    let sm=&s.iter().sum::<isize>();
+    let mut sa=0;
+    for (i,v) in s.iter().enumerate() {
+        sa += v;
+        if sa == *sm {
+            return i as isize;
+        }
+        sa += v;
+    }
+    -1
+}