- Added solutions by Arne Sommer.

- Added solutions by Yitzchak Scott-Thoennes.

29 files changed, 198 insertions, 44 deletions

diff --git a/challenge-331/arne-sommer/blog.txt b/challenge-331/arne-sommer/blog.txt
new file mode 100644
index 0000000000..c4a6aca374
--- /dev/null
+++ b/challenge-331/arne-sommer/blog.txt
@@ -0,0 +1 @@
+https://raku-musings.com/last-buddy.html
diff --git a/challenge-331/arne-sommer/raku/buddy-strings b/challenge-331/arne-sommer/raku/buddy-strings
new file mode 100644
index 0000000000..de7a7672c2
--- /dev/null
+++ b/challenge-331/arne-sommer/raku/buddy-strings
@@ -0,0 +1,31 @@
+#! /usr/bin/env raku
+
+unit sub MAIN ($source where $source.chars > 0,
+               $destination where $destination.chars > 0,
+               :v(:$verbose));
+
+if $destination.chars != $source.chars
+{
+  say ": Different string lengths; { $source.chars } vs { $destination.chars }"
+    if $verbose;
+  say False;
+}
+else
+{
+  my @pairs = $source.comb Z $destination.comb;
+  say ": Pairs: { @pairs.raku }" if $verbose;
+
+  my @changes = @pairs.grep({ $_[0] ne $_[1] });
+  say ": Pairs with changes: { @changes.raku }" if $verbose;
+
+  if @changes.elems == 2
+  {
+    say @changes[0][0] eq @changes[1][1] &&
+        @changes[1][1] eq @changes[0][0];
+  }
+  else
+  {
+    say ": Not two pairs of letters that differ, got { @changes.elems}" if $verbose;
+    say False;
+  }
+}
diff --git a/challenge-331/arne-sommer/raku/buddy-strings-ok b/challenge-331/arne-sommer/raku/buddy-strings-ok
new file mode 100644
index 0000000000..ae91b7cf5a
--- /dev/null
+++ b/challenge-331/arne-sommer/raku/buddy-strings-ok
@@ -0,0 +1,36 @@
+#! /usr/bin/env raku
+
+unit sub MAIN ($source where $source.chars > 0,
+               $destination where $destination.chars > 0,
+               :v(:$verbose));
+
+if $destination.chars != $source.chars
+{
+  say ": Different string lengths; { $source.chars } vs { $destination.chars }"
+    if $verbose;
+  say False;
+}
+else
+{
+  my @pairs = $source.comb Z $destination.comb;
+  say ": Pairs: { @pairs.raku }" if $verbose;
+
+  my @changes = @pairs.grep({ $_[0] ne $_[1] });
+  say ": Pairs with changes: { @changes.raku }" if $verbose;
+
+  if @changes.elems == 2
+  {
+    say @changes[0][0] eq @changes[1][1] &&
+        @changes[1][1] eq @changes[0][0];
+  }
+  elsif @changes.elems == 0 && $source.comb.repeated.elems
+  {
+    say ": Identical strings, but we can swap duplicates" if $verbose;
+    say True;
+  }
+  else
+  {
+    say ": Not two pairs of letters that differ, got { @changes.elems}" if $verbose;
+    say False;
+  }
+}
diff --git a/challenge-331/arne-sommer/raku/ch-1.raku b/challenge-331/arne-sommer/raku/ch-1.raku
new file mode 100644
index 0000000000..72da332298
--- /dev/null
+++ b/challenge-331/arne-sommer/raku/ch-1.raku
@@ -0,0 +1,8 @@
+#! /usr/bin/env raku
+
+unit sub MAIN ($str where $str.chars > 0,
+               :v(:$verbose));
+
+say ": Last word: '{ $str.words.tail }'" if $verbose;
+
+say $str.words.tail.chars;
diff --git a/challenge-331/arne-sommer/raku/ch-2.raku b/challenge-331/arne-sommer/raku/ch-2.raku
new file mode 100644
index 0000000000..ae91b7cf5a
--- /dev/null
+++ b/challenge-331/arne-sommer/raku/ch-2.raku
@@ -0,0 +1,36 @@
+#! /usr/bin/env raku
+
+unit sub MAIN ($source where $source.chars > 0,
+               $destination where $destination.chars > 0,
+               :v(:$verbose));
+
+if $destination.chars != $source.chars
+{
+  say ": Different string lengths; { $source.chars } vs { $destination.chars }"
+    if $verbose;
+  say False;
+}
+else
+{
+  my @pairs = $source.comb Z $destination.comb;
+  say ": Pairs: { @pairs.raku }" if $verbose;
+
+  my @changes = @pairs.grep({ $_[0] ne $_[1] });
+  say ": Pairs with changes: { @changes.raku }" if $verbose;
+
+  if @changes.elems == 2
+  {
+    say @changes[0][0] eq @changes[1][1] &&
+        @changes[1][1] eq @changes[0][0];
+  }
+  elsif @changes.elems == 0 && $source.comb.repeated.elems
+  {
+    say ": Identical strings, but we can swap duplicates" if $verbose;
+    say True;
+  }
+  else
+  {
+    say ": Not two pairs of letters that differ, got { @changes.elems}" if $verbose;
+    say False;
+  }
+}
diff --git a/challenge-331/arne-sommer/raku/last-word b/challenge-331/arne-sommer/raku/last-word
new file mode 100644
index 0000000000..72da332298
--- /dev/null
+++ b/challenge-331/arne-sommer/raku/last-word
@@ -0,0 +1,8 @@
+#! /usr/bin/env raku
+
+unit sub MAIN ($str where $str.chars > 0,
+               :v(:$verbose));
+
+say ": Last word: '{ $str.words.tail }'" if $verbose;
+
+say $str.words.tail.chars;
diff --git a/stats/pwc-current.json b/stats/pwc-current.json
index 60e5109a7a..45c36db081 100644
--- a/stats/pwc-current.json
+++ b/stats/pwc-current.json
@@ -37,6 +37,20 @@
          {
             "data" : [
                [
+                  "Raku",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
+            ],
+            "id" : "Arne Sommer",
+            "name" : "Arne Sommer"
+         },
+         {
+            "data" : [
+               [
                   "Perl",
                   2
                ]
@@ -239,6 +253,16 @@
             ],
             "id" : "W. Luis Mochan",
             "name" : "W. Luis Mochan"
+         },
+         {
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ]
+            ],
+            "id" : "Yitzchak Scott-Thoennes",
+            "name" : "Yitzchak Scott-Thoennes"
          }
       ]
    },
@@ -274,6 +298,11 @@
                "y" : 2
             },
             {
+               "drilldown" : "Arne Sommer",
+               "name" : "Arne Sommer",
+               "y" : 3
+            },
+            {
                "drilldown" : "David Ferrone",
                "name" : "David Ferrone",
                "y" : 2
@@ -357,13 +386,18 @@
                "drilldown" : "W. Luis Mochan",
                "name" : "W. Luis Mochan",
                "y" : 3
+            },
+            {
+               "drilldown" : "Yitzchak Scott-Thoennes",
+               "name" : "Yitzchak Scott-Thoennes",
+               "y" : 2
             }
          ],
          "name" : "The Weekly Challenge - 331"
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 20] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 22] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge - 331"
diff --git a/stats/pwc-language-breakdown-2019.json b/stats/pwc-language-breakdown-2019.json
index 81f224bbf4..aa3facf8f2 100644
--- a/stats/pwc-language-breakdown-2019.json
+++ b/stats/pwc-language-breakdown-2019.json
@@ -970,7 +970,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2020.json b/stats/pwc-language-breakdown-2020.json
index 8f05239412..002f3ee2a0 100644
--- a/stats/pwc-language-breakdown-2020.json
+++ b/stats/pwc-language-breakdown-2020.json
@@ -1223,7 +1223,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2021.json b/stats/pwc-language-breakdown-2021.json
index d63c861ee7..0473b8cfce 100644
--- a/stats/pwc-language-breakdown-2021.json
+++ b/stats/pwc-language-breakdown-2021.json
@@ -1223,7 +1223,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2022.json b/stats/pwc-language-breakdown-2022.json
index f09aec24a4..be0267ead1 100644
--- a/stats/pwc-language-breakdown-2022.json
+++ b/stats/pwc-language-breakdown-2022.json
@@ -1223,7 +1223,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2023.json b/stats/pwc-language-breakdown-2023.json
index 9b9c50f96b..81aadc87ff 100644
--- a/stats/pwc-language-breakdown-2023.json
+++ b/stats/pwc-language-breakdown-2023.json
@@ -1200,7 +1200,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2024.json b/stats/pwc-language-breakdown-2024.json
index 1ad40b38bc..1304738512 100644
--- a/stats/pwc-language-breakdown-2024.json
+++ b/stats/pwc-language-breakdown-2024.json
@@ -1246,7 +1246,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-2025.json b/stats/pwc-language-breakdown-2025.json
index 0412ac8389..9dff469ffa 100644
--- a/stats/pwc-language-breakdown-2025.json
+++ b/stats/pwc-language-breakdown-2025.json
@@ -8,15 +8,15 @@
             "data" : [
                [
                   "Perl",
-                  32
+                  34
                ],
                [
                   "Raku",
-                  14
+                  16
                ],
                [
                   "Blog",
-                  7
+                  8
                ]
             ],
             "id" : "331",
@@ -547,7 +547,7 @@
             {
                "drilldown" : "331",
                "name" : "331",
-               "y" : 53
+               "y" : 58
             },
             {
                "drilldown" : "330",
@@ -694,7 +694,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"
diff --git a/stats/pwc-language-breakdown-summary.json b/stats/pwc-language-breakdown-summary.json
index e65a3b3c53..5488050613 100644
--- a/stats/pwc-language-breakdown-summary.json
+++ b/stats/pwc-language-breakdown-summary.json
@@ -10,15 +10,15 @@
          "data" : [
             [
                "Perl",
-               17086
+               17088
             ],
             [
                "Raku",
-               9509
+               9511
             ],
             [
                "Blog",
-               6115
+               6116
             ]
          ],
          "dataLabels" : {
@@ -37,7 +37,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Contributions [2019 - 2025]"
diff --git a/stats/pwc-leaders.json b/stats/pwc-leaders.json
index b0d81e744c..7ab0d09124 100644
--- a/stats/pwc-leaders.json
+++ b/stats/pwc-leaders.json
@@ -80,11 +80,11 @@
                ],
                [
                   "Raku",
-                  657
+                  659
                ],
                [
                   "Blog",
-                  329
+                  330
                ]
             ],
             "id" : "Arne Sommer",
@@ -817,7 +817,7 @@
             {
                "drilldown" : "Arne Sommer",
                "name" : "5: Arne Sommer",
-               "y" : 2278
+               "y" : 2284
             },
             {
                "drilldown" : "Athanasius",
@@ -1049,7 +1049,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the score breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the score breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "Team Leaders (TOP 50)"
diff --git a/stats/pwc-summary-1-30.json b/stats/pwc-summary-1-30.json
index 76acd9d2eb..4c0c0cb228 100644
--- a/stats/pwc-summary-1-30.json
+++ b/stats/pwc-summary-1-30.json
@@ -72,7 +72,7 @@
             0,
             0,
             2,
-            657,
+            659,
             0,
             21
          ],
@@ -107,7 +107,7 @@
             0,
             0,
             0,
-            329,
+            330,
             0,
             0
          ],
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-121-150.json b/stats/pwc-summary-121-150.json
index 684d81ca61..ac1509f595 100644
--- a/stats/pwc-summary-121-150.json
+++ b/stats/pwc-summary-121-150.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-151-180.json b/stats/pwc-summary-151-180.json
index 3bb2164dc8..9bbf009f7f 100644
--- a/stats/pwc-summary-151-180.json
+++ b/stats/pwc-summary-151-180.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-181-210.json b/stats/pwc-summary-181-210.json
index 0ea91a414f..bde52174c1 100644
--- a/stats/pwc-summary-181-210.json
+++ b/stats/pwc-summary-181-210.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-211-240.json b/stats/pwc-summary-211-240.json
index f5fbc161f6..73e3463b64 100644
--- a/stats/pwc-summary-211-240.json
+++ b/stats/pwc-summary-211-240.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-241-270.json b/stats/pwc-summary-241-270.json
index bdb1a011ee..30ef9950fc 100644
--- a/stats/pwc-summary-241-270.json
+++ b/stats/pwc-summary-241-270.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-271-300.json b/stats/pwc-summary-271-300.json
index ad52ac9382..b4d8867d0a 100644
--- a/stats/pwc-summary-271-300.json
+++ b/stats/pwc-summary-271-300.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-301-330.json b/stats/pwc-summary-301-330.json
index 923fb1986c..8d010b7a78 100644
--- a/stats/pwc-summary-301-330.json
+++ b/stats/pwc-summary-301-330.json
@@ -34,7 +34,7 @@
             3,
             3,
             85,
-            18,
+            20,
             21,
             8
          ],
@@ -106,7 +106,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 27] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 27] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-31-60.json b/stats/pwc-summary-31-60.json
index bc2ff816c6..1a45caee54 100644
--- a/stats/pwc-summary-31-60.json
+++ b/stats/pwc-summary-31-60.json
@@ -69,8 +69,8 @@
             9,
             0,
             0,
-            2,
             17,
+            2,
             0,
             194,
             0,
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-61-90.json b/stats/pwc-summary-61-90.json
index 8075f30cf3..02b23be63e 100644
--- a/stats/pwc-summary-61-90.json
+++ b/stats/pwc-summary-61-90.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary-91-120.json b/stats/pwc-summary-91-120.json
index f28ec87694..d4158fec02 100644
--- a/stats/pwc-summary-91-120.json
+++ b/stats/pwc-summary-91-120.json
@@ -115,7 +115,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 30] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 30] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-summary.json b/stats/pwc-summary.json
index a091e0746e..e5a1cc5af3 100644
--- a/stats/pwc-summary.json
+++ b/stats/pwc-summary.json
@@ -334,7 +334,7 @@
             3,
             3,
             44,
-            9,
+            10,
             11,
             4
          ],
@@ -369,7 +369,7 @@
             0,
             0,
             1,
-            329,
+            330,
             0,
             12,
             280,
@@ -701,7 +701,7 @@
             0,
             0,
             0,
-            329,
+            330,
             0,
             0,
             4,
@@ -1006,7 +1006,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "[Champions: 327] Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "[Champions: 327] Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge [2019 - 2025]"
diff --git a/stats/pwc-yearly-language-summary.json b/stats/pwc-yearly-language-summary.json
index 099e3f9eb9..22dd2f3411 100644
--- a/stats/pwc-yearly-language-summary.json
+++ b/stats/pwc-yearly-language-summary.json
@@ -8,15 +8,15 @@
             "data" : [
                [
                   "Perl",
-                  1315
+                  1317
                ],
                [
                   "Raku",
-                  639
+                  641
                ],
                [
                   "Blog",
-                  536
+                  537
                ]
             ],
             "id" : "2025",
@@ -151,7 +151,7 @@
             {
                "drilldown" : "2025",
                "name" : "2025",
-               "y" : 2490
+               "y" : 2495
             },
             {
                "drilldown" : "2024",
@@ -188,7 +188,7 @@
       }
    ],
    "subtitle" : {
-      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 18:42:21 GMT"
+      "text" : "Click the columns to drilldown the language breakdown. Last updated at 2025-07-23 21:29:25 GMT"
    },
    "title" : {
       "text" : "The Weekly Challenge Language"