Merge pull request #7174 from Firedrake/rogerbw-challenge-193

Solutions for challenge #193

18 files changed, 762 insertions, 0 deletions

diff --git a/challenge-193/roger-bell-west/javascript/ch-1.js b/challenge-193/roger-bell-west/javascript/ch-1.js
new file mode 100755
index 0000000000..31d8f7fdcc
--- /dev/null
+++ b/challenge-193/roger-bell-west/javascript/ch-1.js
@@ -0,0 +1,51 @@
+#! /usr/bin/node
+
+"use strict"
+
+function deepEqual(a,b)
+{
+    if( (typeof a == 'object' && a != null) &&
+        (typeof b == 'object' && b != null) )
+    {
+        var count = [0,0];
+        for( var key in a) count[0]++;
+        for( var key in b) count[1]++;
+        if( count[0]-count[1] != 0) {return false;}
+        for( var key in a)
+        {
+            if(!(key in b) || !deepEqual(a[key],b[key])) {return false;}
+        }
+        for( var key in b)
+        {
+            if(!(key in a) || !deepEqual(b[key],a[key])) {return false;}
+        }
+        return true;
+    }
+    else
+    {
+        return a === b;
+    }
+}
+
+function binarystring(n) {
+    let o = [];
+    let t = 1 << n;
+    for (let a = 0; a < t; a++) {
+        o.push(a.toString(2).padStart(n, "0"));
+    }
+    return o;
+}
+
+if (deepEqual(binarystring(2), ["00", "01", "10", "11"])) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+
+if (deepEqual(binarystring(3), ["000", "001", "010", "011", "100", "101", "110", "111"])) {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-193/roger-bell-west/javascript/ch-2.js b/challenge-193/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..4d3db17e38
--- /dev/null
+++ b/challenge-193/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,38 @@
+#! /usr/bin/node
+
+"use strict"
+
+function oddstring(ss) {
+    let t = ss[0].length - 1;
+    for (let i = 0; i < t; i++) {
+        let tab = new Map();
+        for (let s of ss) {
+            let v = s.charCodeAt(i+1) - s.charCodeAt(i);
+            let ll = [];
+            if (tab.has(v)) {
+                ll = tab.get(v);
+            }
+            ll.push(s);
+            tab.set(v,ll);
+        }
+        for (let j of tab.values()) {
+            if (j.length == 1) {
+                return j[0];
+            }
+        }
+    }
+    return "";
+}
+
+if (oddstring(["adc", "wzy", "abc"]) == "abc") {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (oddstring(["aaa", "bob", "ccc", "ddd"]) == "bob") {
+    process.stdout.write("Pass");
+} else {
+    process.stdout.write("FAIL");
+}
+process.stdout.write("\n");
diff --git a/challenge-193/roger-bell-west/kotlin/ch-1.kt b/challenge-193/roger-bell-west/kotlin/ch-1.kt
new file mode 100644
index 0000000000..b859674709
--- /dev/null
+++ b/challenge-193/roger-bell-west/kotlin/ch-1.kt
@@ -0,0 +1,22 @@
+fun binarystring(n: Int): List<String> {
+    var o = ArrayList<String>()
+    for (a in 0..(1 shl n)-1) {
+        o.add(Integer.toBinaryString(a).padStart(n, '0'))
+    }
+    return o.toList()
+}
+
+fun main() {
+    if (binarystring(2) == listOf("00", "01", "10", "11")) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")
+    if (binarystring(3) == listOf("000", "001", "010", "011", "100", "101", "110", "111")) {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-193/roger-bell-west/kotlin/ch-2.kt b/challenge-193/roger-bell-west/kotlin/ch-2.kt
new file mode 100644
index 0000000000..c7edac6e64
--- /dev/null
+++ b/challenge-193/roger-bell-west/kotlin/ch-2.kt
@@ -0,0 +1,34 @@
+import kotlin.math.*
+
+fun oddstring(ss: List<String>): String {
+    for (i in 0..ss[0].length-2) {
+        var tab = mutableMapOf<Int, ArrayList<String>>()
+        for (s in ss) {
+            val v = s[i+1].code - s[i].code
+            var ll = tab.getOrDefault(v, ArrayList<String>())
+            ll.add(s)
+            tab.put(v, ll)
+        }
+        for (j in tab.values) {
+            if (j.size == 1) {
+                return j[0]
+            }
+        }
+    }
+    return ""
+}
+
+fun main() {
+    if (oddstring(listOf("adc", "wzy", "abc")) == "abc") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    print(" ")   
+    if (oddstring(listOf("aaa", "bob", "ccc", "ddd")) == "bob") {
+        print("Pass")
+    } else {
+        print("FAIL")
+    }
+    println("")
+}
diff --git a/challenge-193/roger-bell-west/lua/ch-1.lua b/challenge-193/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..59d2e8ee69
--- /dev/null
+++ b/challenge-193/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,59 @@
+#! /usr/bin/lua
+
+function recursive_compare(t1,t2)
+   -- Use usual comparison first.
+   if t1==t2 then return true end
+   -- We only support non-default behavior for tables
+   if (type(t1)~="table") then return false end
+   -- They better have the same metatables
+   local mt1 = getmetatable(t1)
+   local mt2 = getmetatable(t2)
+   if( not recursive_compare(mt1,mt2) ) then return false end
+
+   -- Check each key-value pair
+   -- We have to do this both ways in case we miss some.
+   -- TODO: Could probably be smarter and not check those we've 
+   -- already checked though!
+   for k1,v1 in pairs(t1) do
+      local v2 = t2[k1]
+      if( not recursive_compare(v1,v2) ) then return false end
+   end
+   for k2,v2 in pairs(t2) do
+      local v1 = t1[k2]
+      if( not recursive_compare(v1,v2) ) then return false end
+   end
+
+   return true  
+end
+
+function tobase(val0, len, base)
+   local s = ""
+   local val = val0
+   for i = 1, len do
+      s = tostring(val % base) .. s
+      val = val // base
+   end
+   return s
+end
+
+function binarystring(n)
+   local o = {}
+   for a = 0,(1 << n)-1 do
+      table.insert(o,tobase(a, n, 2))
+   end
+   return o
+end
+
+if recursive_compare(binarystring(2), {"00", "01", "10", "11"}) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if recursive_compare(binarystring(3), {"000", "001", "010", "011", "100", "101", "110", "111"}) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-193/roger-bell-west/lua/ch-2.lua b/challenge-193/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..dc3c034b72
--- /dev/null
+++ b/challenge-193/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,35 @@
+#! /usr/bin/lua
+
+function oddstring(ss)
+   for i = 1,#(ss[1])-1 do
+      local tab = {}
+      for p,s in ipairs(ss) do
+         local v = string.byte(s, i+1) - string.byte(s, i)
+         if tab[v] == nil then
+            tab[v] = { s }
+         else
+            table.insert(tab[v], s)
+         end
+      end
+      for i,j in pairs(tab) do
+         if #j == 1 then
+            return j[1]
+         end
+      end
+   end
+   return ""
+end
+
+if oddstring({"adc", "wzy", "abc"}) == "abc" then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if oddstring({"aaa", "bob", "ccc", "ddd"}) == "bob" then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-193/roger-bell-west/perl/ch-1.pl b/challenge-193/roger-bell-west/perl/ch-1.pl
new file mode 100755
index 0000000000..8228f91103
--- /dev/null
+++ b/challenge-193/roger-bell-west/perl/ch-1.pl
@@ -0,0 +1,18 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 2;
+
+is_deeply(binarystring(2), ["00", "01", "10", "11"], 'example 1');
+is_deeply(binarystring(3), ["000", "001", "010", "011", "100", "101", "110", "111"], 'example 2');
+
+sub binarystring($n) {
+  my @o;
+  foreach my $a (0..(1 << $n)-1) {
+    push @o,sprintf('%0'.$n.'b', $a);
+  }
+  return \@o;
+}
diff --git a/challenge-193/roger-bell-west/perl/ch-2.pl b/challenge-193/roger-bell-west/perl/ch-2.pl
new file mode 100755
index 0000000000..855f08d616
--- /dev/null
+++ b/challenge-193/roger-bell-west/perl/ch-2.pl
@@ -0,0 +1,26 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+use experimental 'signatures';
+
+use Test::More tests => 2;
+
+is(oddstring(["adc", "wzy", "abc"]), "abc", 'example 1');
+is(oddstring(["aaa", "bob", "ccc", "ddd"]), "bob", 'example 2');
+
+sub oddstring($ss) {
+  foreach my $i (0..length($ss->[0])-2) {
+    my %tab;
+    foreach my $s (@{$ss}) {
+      my $v = ord(substr($s,$i+1,1)) - ord(substr($s,$i,1));
+      push @{$tab{$v}}, $s;
+    }
+    foreach my $j (values %tab) {
+      if (scalar @{$j} == 1) {
+        return $j->[0];
+      }
+    }
+  }
+  return '';
+}
diff --git a/challenge-193/roger-bell-west/postscript/ch-1.ps b/challenge-193/roger-bell-west/postscript/ch-1.ps
new file mode 100644
index 0000000000..573bc3af0f
--- /dev/null
+++ b/challenge-193/roger-bell-west/postscript/ch-1.ps
@@ -0,0 +1,133 @@
+%!PS
+
+% begin included library code
+% see https://github.com/Firedrake/postscript-libraries/
+/safestring {
+    dup length string cvs
+} 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.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} 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.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 included library code
+
+/binarystring {
+    5 dict begin
+    /n exch def
+    /zero n string def
+    0 1 n 1 sub {
+        zero exch 48 put
+    } for
+    [
+        0 1 1 n bitshift 1 sub {
+            /a exch def
+            /i n 1 sub def
+            /str zero safestring def
+            {
+                a 0 gt {
+                    a 1 and 0 gt {
+                      str i 49 put
+                    } if
+                    /i i 1 sub def
+                    /a a -1 bitshift def
+                } {
+                    exit
+                } ifelse
+            } loop
+            str
+        } for
+    ]
+    end
+} bind def
+
+(binarystring) test.start
+2 binarystring [(00) (01) (10) (11)] deepeq test
+3 binarystring [(000) (001) (010) (011) (100) (101) (110) (111)] deepeq test
+test.end
diff --git a/challenge-193/roger-bell-west/postscript/ch-2.ps b/challenge-193/roger-bell-west/postscript/ch-2.ps
new file mode 100644
index 0000000000..3368c453b5
--- /dev/null
+++ b/challenge-193/roger-bell-west/postscript/ch-2.ps
@@ -0,0 +1,152 @@
+%!PS
+
+% begin included library code
+% see https://github.com/Firedrake/postscript-libraries/
+/test.start {
+    print (:) print
+    /test.pass 0 def
+    /test.count 0 def
+} 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
+
+/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
+
+/values { % dict -> array of dict values
+    [ exch
+      {
+          exch pop
+      } forall
+    ]
+} bind def
+
+/safestring {
+    dup length string cvs
+} 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
+
+/apush.right { % [a b] c -> [a b c]
+    exch
+    [ exch aload length 2 add -1 roll ]
+} bind def
+
+
+% end included library code
+
+/oddstring {
+    6 dict begin
+    /ss exch def
+    /ex () def
+    0 1 ss 0 get length 2 sub {
+        /i exch def
+        /tab 0 dict def
+        ss {
+            /s exch def
+            /v s i 1 add get s i get sub def
+            tab v known {
+                tab v get
+            } {
+                0 array
+            } ifelse
+            s safestring apush.right
+            tab exch v exch put
+        } forall
+        tab values {
+            dup length 1 eq {
+                0 get
+                /ex exch def
+                exit
+            } {
+                pop
+            } ifelse
+        } forall
+        ex () deepeq not {
+            exit
+        } if
+    } for
+    ex
+    end
+} bind def
+
+(oddstring) test.start
+[ (adc) (wzy) (abc) ] oddstring (abc) deepeq test
+[ (aaa) (bob) (ccc) (ddd) ] oddstring (bob) deepeq test
+test.end
diff --git a/challenge-193/roger-bell-west/python/ch-1.py b/challenge-193/roger-bell-west/python/ch-1.py
new file mode 100755
index 0000000000..473c8977c9
--- /dev/null
+++ b/challenge-193/roger-bell-west/python/ch-1.py
@@ -0,0 +1,19 @@
+#! /usr/bin/python3
+
+import unittest
+
+def binarystring(n):
+  o = []
+  for a in range(1 << n):
+    o.append("{0:0>{w}b}".format(a, w=n))
+  return o
+
+class TestBinarystring(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(binarystring(2), ["00", "01", "10", "11"], 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(binarystring(3), ["000", "001", "010", "011", "100", "101", "110", "111"], 'example 2')
+
+unittest.main()
diff --git a/challenge-193/roger-bell-west/python/ch-2.py b/challenge-193/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..e68c819eec
--- /dev/null
+++ b/challenge-193/roger-bell-west/python/ch-2.py
@@ -0,0 +1,24 @@
+#! /usr/bin/python3
+
+import unittest
+from collections import defaultdict
+
+def oddstring(ss):
+  for i in range(len(ss[0])-1):
+    tab = defaultdict(list)
+    for s in ss:
+      tab[ord(s[i+1]) - ord(s[i])].append(s)
+    for j in tab.values():
+      if len(j) == 1:
+        return j[0]
+  return ""
+
+class TestOddstring(unittest.TestCase):
+
+  def test_ex1(self):
+    self.assertEqual(oddstring(["adc", "wzy", "abc"]), "abc", "example 1")
+
+  def test_ex2(self):
+    self.assertEqual(oddstring(["aaa", "bob", "ccc", "ddd"]), "bob", "example 2")
+
+unittest.main()
diff --git a/challenge-193/roger-bell-west/raku/ch-1.p6 b/challenge-193/roger-bell-west/raku/ch-1.p6
new file mode 100755
index 0000000000..3adaa2675e
--- /dev/null
+++ b/challenge-193/roger-bell-west/raku/ch-1.p6
@@ -0,0 +1,16 @@
+#! /usr/bin/perl6
+
+use Test;
+
+plan 2;
+
+is-deeply(binarystring(2), ["00", "01", "10", "11"], 'example 1');
+is-deeply(binarystring(3), ["000", "001", "010", "011", "100", "101", "110", "111"], 'example 2');
+
+sub binarystring($n) {
+  my @o;
+  for (0..(1 +< $n)-1) -> $a {
+    @o.push(sprintf('%0' ~ $n ~ 'b', $a));
+  }
+  return @o;
+}
diff --git a/challenge-193/roger-bell-west/raku/ch-2.p6 b/challenge-193/roger-bell-west/raku/ch-2.p6
new file mode 100755
index 0000000000..dd692bdf29
--- /dev/null
+++ b/challenge-193/roger-bell-west/raku/ch-2.p6
@@ -0,0 +1,24 @@
+#! /usr/bin/perl6
+
+use Test;
+
+plan 2;
+
+is(oddstring(["adc", "wzy", "abc"]), "abc", 'example 1');
+is(oddstring(["aaa", "bob", "ccc", "ddd"]), "bob", 'example 2');
+
+sub oddstring(@ss) {
+  for (0..chars(@ss[0])-2) -> $i {
+    my %tab;
+    for @ss -> $s {
+      my $v = ord(substr($s,$i+1,1)) - ord(substr($s,$i,1));
+      %tab{$v}.push($s);
+    }
+    for (%tab.values) -> @j {
+      if (@j.elems == 1) {
+        return @j[0];
+      }
+    }
+  }
+  return '';
+}
diff --git a/challenge-193/roger-bell-west/ruby/ch-1.rb b/challenge-193/roger-bell-west/ruby/ch-1.rb
new file mode 100755
index 0000000000..aeefefa41d
--- /dev/null
+++ b/challenge-193/roger-bell-west/ruby/ch-1.rb
@@ -0,0 +1,25 @@
+#! /usr/bin/ruby
+
+require 'test/unit'
+
+require 'set'
+
+def binarystring(n)
+  fmt = "%0" + n.to_s + "b"
+  o = []
+  0.upto((1 << n)-1) do |a|
+    o.push(sprintf(fmt, a))
+  end
+  return o
+end
+
+class TestBinarystring < Test::Unit::TestCase
+
+  def test_ex1
+    assert_equal(["00", "01", "10", "11"], binarystring(2));
+  end
+
+  def test_ex2
+    assert_equal(["000", "001", "010", "011", "100", "101", "110", "111"], binarystring(3));
+  end
+end
diff --git a/challenge-193/roger-bell-west/ruby/ch-2.rb b/challenge-193/roger-bell-west/ruby/ch-2.rb
new file mode 100755
index 0000000000..fefb1c4d50
--- /dev/null
+++ b/challenge-193/roger-bell-west/ruby/ch-2.rb
@@ -0,0 +1,35 @@
+#! /usr/bin/ruby
+
+require 'test/unit'
+
+def oddstring(ss)
+  0.upto(ss[0].length-2) do |i|
+    tab = Hash.new
+    ss.each do |s|
+      v = s[i+1].ord - s[i].ord
+      l = []
+      if tab.has_key?(v) then
+        l = tab[v]
+      end
+      l.push(s)
+      tab[v] = l
+    end
+    tab.values().each do |j|
+      if j.length == 1 then
+        return j[0]
+      end
+    end
+  end
+  return ""
+end
+
+class TestOddstring < Test::Unit::TestCase
+
+  def test_ex1
+    assert_equal("abc", oddstring(["adc", "wzy", "abc"]))
+  end
+
+  def test_ex2
+    assert_equal("bob", oddstring(["aaa", "bob", "ccc", "ddd"]))
+  end
+end
diff --git a/challenge-193/roger-bell-west/rust/ch-1.rs b/challenge-193/roger-bell-west/rust/ch-1.rs
new file mode 100755
index 0000000000..77f3c1d208
--- /dev/null
+++ b/challenge-193/roger-bell-west/rust/ch-1.rs
@@ -0,0 +1,20 @@
+#! /bin/sh
+//usr/bin/env rustc --test $0 -o ${0}x && ./${0}x --nocapture; rm -f ${0}x ; exit
+
+#[test]
+fn test_ex1() {
+    assert_eq!(binarystring(2), vec!["00", "01", "10", "11"]);
+}
+
+#[test]
+fn test_ex2() {
+    assert_eq!(binarystring(3), vec!["000", "001", "010", "011", "100", "101", "110", "111"]);
+}
+
+fn binarystring(n: usize) -> Vec<String> {
+    let mut o = Vec::new();
+    for a in 0..(1<<n) {
+        o.push(format!("{:0width$b}", a, width = n));
+    }
+    o
+}
diff --git a/challenge-193/roger-bell-west/rust/ch-2.rs b/challenge-193/roger-bell-west/rust/ch-2.rs
new file mode 100755
index 0000000000..b43addc64c
--- /dev/null
+++ b/challenge-193/roger-bell-west/rust/ch-2.rs
@@ -0,0 +1,31 @@
+#! /bin/sh
+//usr/bin/env rustc --test $0 -o ${0}x && ./${0}x --nocapture; rm -f ${0}x ; exit
+
+use std::collections::HashMap;
+
+#[test]
+fn test_ex1() {
+    assert_eq!(oddstring(vec!["adc", "wzy", "abc"]), "abc");
+}
+
+#[test]
+fn test_ex2() {
+    assert_eq!(oddstring(vec!["aaa", "bob", "ccc", "ddd"]), "bob");
+}
+
+fn oddstring(ss: Vec<&str>) -> String {
+   for i in 0..=ss[0].len()-2 {
+        let mut tab: HashMap<usize, Vec<&str>> = HashMap::new();
+       for s in &ss {
+           let v = (s.chars().nth(i+1).unwrap() as usize) - (s.chars().nth(i).unwrap() as usize);
+           let l = tab.entry(v).or_insert(Vec::new());
+           l.push(s);
+       }
+       for j in tab.values() {
+           if j.len() == 1 {
+               return j[0].to_string();
+           }
+       }
+    }
+    "".to_string()
+}