From a99887954590dddced0c6110f360e11040c7a641 Mon Sep 17 00:00:00 2001
From: meatball <69751659+meatball133@users.noreply.github.com>
Date: Fri, 6 Dec 2024 16:28:19 +0100
Subject: [PATCH 1/5] Fixes to concept tree

---
 misc/concept_tree.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/misc/concept_tree.md b/misc/concept_tree.md
index b89d34b2..ff207ae8 100644
--- a/misc/concept_tree.md
+++ b/misc/concept_tree.md
@@ -1,7 +1,7 @@
 # Concept Tree
 
 This is a concept tree for the Crystal Syllabus. 
-It is a work in progress, it was last updated on 2024-01-13.
+It is a work in progress, it was last updated on 2024-12-06.
 Each concept with an exercise around it has been implemented, the rest is still to be implemented.
 
 
@@ -16,7 +16,7 @@ graph TD
         b(bools)
     end
 
-    subgraph J [Number Types]
+    subgraph J [Navigation Computer]
         ac(Number Types)
     end
 
@@ -48,7 +48,7 @@ graph TD
         h(conditionals)
     end
 
-    subgraph I [Interest is intresting]
+    subgraph I [Interest is interesting]
         i(return)
         j(while)
     end

From 89ffdb7d1e9a36f21df3baccc6d5e19a31e3b185 Mon Sep 17 00:00:00 2001
From: meatball <meatballsofmeatballs@gmail.com>
Date: Fri, 2 Jan 2026 19:19:47 +0100
Subject: [PATCH 2/5] Add Baffling Birthdays exercise with instructions,
 example, and tests

---
 config.json                                   |  8 ++
 .../baffling-birthdays/.docs/instructions.md  | 23 +++++
 .../baffling-birthdays/.docs/introduction.md  | 25 +++++
 .../baffling-birthdays/.meta/config.json      | 19 ++++
 .../baffling-birthdays/.meta/src/example.cr   | 29 ++++++
 .../.meta/test_template.ecr                   | 31 ++++++
 .../baffling-birthdays/.meta/tests.toml       | 61 ++++++++++++
 .../spec/baffling_birthdays_spec.cr           | 96 +++++++++++++++++++
 .../src/baffling_birthdays.cr                 | 12 +++
 9 files changed, 304 insertions(+)
 create mode 100644 exercises/practice/baffling-birthdays/.docs/instructions.md
 create mode 100644 exercises/practice/baffling-birthdays/.docs/introduction.md
 create mode 100644 exercises/practice/baffling-birthdays/.meta/config.json
 create mode 100644 exercises/practice/baffling-birthdays/.meta/src/example.cr
 create mode 100644 exercises/practice/baffling-birthdays/.meta/test_template.ecr
 create mode 100644 exercises/practice/baffling-birthdays/.meta/tests.toml
 create mode 100644 exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
 create mode 100644 exercises/practice/baffling-birthdays/src/baffling_birthdays.cr

diff --git a/config.json b/config.json
index 4a708598..0d736d20 100644
--- a/config.json
+++ b/config.json
@@ -1036,6 +1036,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "baffling-birthdays",
+        "name": "Baffling Birthdays",
+        "uuid": "232e58b6-06ca-4401-b4ba-2e16e59902c3",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "food-chain",
         "name": "Food Chain",
diff --git a/exercises/practice/baffling-birthdays/.docs/instructions.md b/exercises/practice/baffling-birthdays/.docs/instructions.md
new file mode 100644
index 00000000..a01ec867
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.docs/instructions.md
@@ -0,0 +1,23 @@
+# Instructions
+
+Your task is to estimate the birthday paradox's probabilities.
+
+To do this, you need to:
+
+- Generate random birthdates.
+- Check if a collection of randomly generated birthdates contains at least two with the same birthday.
+- Estimate the probability that at least two people in a group share the same birthday for different group sizes.
+
+~~~~exercism/note
+A birthdate includes the full date of birth (year, month, and day), whereas a birthday refers only to the month and day, which repeat each year.
+Two birthdates with the same month and day correspond to the same birthday.
+~~~~
+
+~~~~exercism/caution
+The birthday paradox assumes that:
+
+- There are 365 possible birthdays (no leap years).
+- Each birthday is equally likely (uniform distribution).
+
+Your implementation must follow these assumptions.
+~~~~
diff --git a/exercises/practice/baffling-birthdays/.docs/introduction.md b/exercises/practice/baffling-birthdays/.docs/introduction.md
new file mode 100644
index 00000000..97dabd1e
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.docs/introduction.md
@@ -0,0 +1,25 @@
+# Introduction
+
+Fresh out of college, you're throwing a huge party to celebrate with friends and family.
+Over 70 people have shown up, including your mildly eccentric Uncle Ted.
+
+In one of his usual antics, he bets you £100 that at least two people in the room share the same birthday.
+That sounds ridiculous — there are many more possible birthdays than there are guests, so you confidently accept.
+
+To your astonishment, after collecting the birthdays of just 32 guests, you've already found two guests that share the same birthday.
+Accepting your loss, you hand Uncle Ted his £100, but something feels off.
+
+The next day, curiosity gets the better of you.
+A quick web search leads you to the [birthday paradox][birthday-problem], which reveals that with just 23 people, the probability of a shared birthday exceeds 50%.
+
+Ah. So _that's_ why Uncle Ted was so confident.
+
+Determined to turn the tables, you start looking up other paradoxes; next time, _you'll_ be the one making the bets.
+
+~~~~exercism/note
+The birthday paradox is a [veridical paradox][veridical-paradox]: even though it feels wrong, it is actually true.
+
+[veridical-paradox]: https://en.wikipedia.org/wiki/Paradox#Quine's_classification
+~~~~
+
+[birthday-problem]: https://en.wikipedia.org/wiki/Birthday_problem
diff --git a/exercises/practice/baffling-birthdays/.meta/config.json b/exercises/practice/baffling-birthdays/.meta/config.json
new file mode 100644
index 00000000..f8be9d4e
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.meta/config.json
@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "meatball133"
+  ],
+  "files": {
+    "solution": [
+      "src/baffling_birthdays.cr"
+    ],
+    "test": [
+      "spec/baffling_birthdays_spec.cr"
+    ],
+    "example": [
+      ".meta/src/example.cr"
+    ]
+  },
+  "blurb": "Estimate the birthday paradox's probabilities.",
+  "source": "Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/pull/2539"
+}
diff --git a/exercises/practice/baffling-birthdays/.meta/src/example.cr b/exercises/practice/baffling-birthdays/.meta/src/example.cr
new file mode 100644
index 00000000..a7bceb6d
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.meta/src/example.cr
@@ -0,0 +1,29 @@
+class BafflingBirthdays
+  def self.shared_birthday(birthdates : Array(Time)) : Bool
+    birthdates.each_with_index do |date, idx|
+      birthdates.each_with_index do |date_2, idx_2|
+        if idx == idx_2
+          next
+        end
+        if date.month == date_2.month && date.day == date_2.day
+          return true
+        end
+      end
+    end
+    return false
+  end
+
+  def self.random_birthdates(size : Int) : Array(Time)
+    result = [] of Time
+    size.times do |_|
+      time = Time.utc(2025, 1, 1).shift days: Random.rand(356)
+      result << time
+    end
+
+    return result
+  end
+
+  def self.estimated_probability_of_shared_birthday(size : Int) : Float
+    return (1..10000).sum {|_| shared_birthday(random_birthdates(size)) ? 1 : 0} / 100.0
+  end
+end
diff --git a/exercises/practice/baffling-birthdays/.meta/test_template.ecr b/exercises/practice/baffling-birthdays/.meta/test_template.ecr
new file mode 100644
index 00000000..59612a17
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.meta/test_template.ecr
@@ -0,0 +1,31 @@
+require "spec"
+require "../src/*"
+
+describe "<%-= to_capitalized(@json["exercise"].to_s) %>" do
+<%- @json["cases"].as_a.each do |cases| %>
+    <%- cases["cases"].as_a.each do |sub_case| %>
+    <%= status()%> "<%-= sub_case["description"] %>" do
+        <%- if sub_case["property"] == "sharedBirthday" -%>
+            birthdays = [<%= sub_case["input"]["birthdates"].as_a.map {|date| "Time.parse_utc(\"#{date}\",  \"%Y-%m-%d\")" }.join(", ") %>]
+            <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(birthdays).should be_<%= sub_case["expected"] %>
+        <%- elsif sub_case["property"] == "estimatedProbabilityOfSharedBirthday" -%>
+            <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(<%= sub_case["input"]["groupSize"] %>).should be_close <%= (sub_case["expected"]) %>, <%= sub_case["input"]["groupSize"].as_i == 23 ? 1.5 : sub_case["input"]["groupSize"].as_i == 1 ? 0.01 : 1  %>
+        <%- elsif sub_case["expected"] == "length == groupsize" -%>
+            (1..10).each do |size|
+                result = <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(size)
+                result.size.should eq(size)
+            end
+        <%- elsif (sub_case["expected"]["years"]? || {} of String => Bool)["leapYear"]? -%>
+            result = <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(50)
+            result.all? { |date| Time.leap_year?(date.year) }.should be_false
+        <%- elsif (sub_case["expected"]["months"]? || {} of String => Bool)["random"]? -%>
+            result = <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(100)
+            result.to_set { |date| date.month }.size.should eq(12)
+        <%- elsif (sub_case["expected"]["days"]? || {} of String => Bool)["random"]? -%>
+            result = <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(300)
+            result.to_set { |date| date.day }.size.should eq(31)
+        <% end %>
+    end
+    <% end %>
+<% end %>
+end
diff --git a/exercises/practice/baffling-birthdays/.meta/tests.toml b/exercises/practice/baffling-birthdays/.meta/tests.toml
new file mode 100644
index 00000000..c76afb46
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/.meta/tests.toml
@@ -0,0 +1,61 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[716dcc2b-8fe4-4fc9-8c48-cbe70d8e6b67]
+description = "shared birthday -> one birthdate"
+
+[f7b3eb26-bcfc-4c1e-a2de-af07afc33f45]
+description = "shared birthday -> two birthdates with same year, month, and day"
+
+[7193409a-6e16-4bcb-b4cc-9ffe55f79b25]
+description = "shared birthday -> two birthdates with same year and month, but different day"
+
+[d04db648-121b-4b72-93e8-d7d2dced4495]
+description = "shared birthday -> two birthdates with same month and day, but different year"
+
+[3c8bd0f0-14c6-4d4c-975a-4c636bfdc233]
+description = "shared birthday -> two birthdates with same year, but different month and day"
+
+[df5daba6-0879-4480-883c-e855c99cdaa3]
+description = "shared birthday -> two birthdates with different year, month, and day"
+
+[0c17b220-cbb9-4bd7-872f-373044c7b406]
+description = "shared birthday -> multiple birthdates without shared birthday"
+
+[966d6b0b-5c0a-4b8c-bc2d-64939ada49f8]
+description = "shared birthday -> multiple birthdates with one shared birthday"
+
+[b7937d28-403b-4500-acce-4d9fe3a9620d]
+description = "shared birthday -> multiple birthdates with more than one shared birthday"
+
+[70b38cea-d234-4697-b146-7d130cd4ee12]
+description = "random birthdates -> generate requested number of birthdates"
+
+[d9d5b7d3-5fea-4752-b9c1-3fcd176d1b03]
+description = "random birthdates -> years are not leap years"
+
+[d1074327-f68c-4c8a-b0ff-e3730d0f0521]
+description = "random birthdates -> months are random"
+
+[7df706b3-c3f5-471d-9563-23a4d0577940]
+description = "random birthdates -> days are random"
+
+[89a462a4-4265-4912-9506-fb027913f221]
+description = "estimated probability of at least one shared birthday -> for one person"
+
+[ec31c787-0ebb-4548-970c-5dcb4eadfb5f]
+description = "estimated probability of at least one shared birthday -> among ten people"
+
+[b548afac-a451-46a3-9bb0-cb1f60c48e2f]
+description = "estimated probability of at least one shared birthday -> among twenty-three people"
+
+[e43e6b9d-d77b-4f6c-a960-0fc0129a0bc5]
+description = "estimated probability of at least one shared birthday -> among seventy people"
diff --git a/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
new file mode 100644
index 00000000..45ffc50f
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
@@ -0,0 +1,96 @@
+require "spec"
+require "../src/*"
+
+describe "BafflingBirthdays" do
+  it "one birthdate" do
+    birthdays = [Time.parse_utc("2000-01-01", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_false
+  end
+
+  pending "two birthdates with same year, month, and day" do
+    birthdays = [Time.parse_utc("2000-01-01", "%Y-%m-%d"), Time.parse_utc("2000-01-01", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_true
+  end
+
+  pending "two birthdates with same year and month, but different day" do
+    birthdays = [Time.parse_utc("2012-05-09", "%Y-%m-%d"), Time.parse_utc("2012-05-17", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_false
+  end
+
+  pending "two birthdates with same month and day, but different year" do
+    birthdays = [Time.parse_utc("1999-10-23", "%Y-%m-%d"), Time.parse_utc("1988-10-23", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_true
+  end
+
+  pending "two birthdates with same year, but different month and day" do
+    birthdays = [Time.parse_utc("2007-12-19", "%Y-%m-%d"), Time.parse_utc("2007-04-27", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_false
+  end
+
+  pending "two birthdates with different year, month, and day" do
+    birthdays = [Time.parse_utc("1997-08-04", "%Y-%m-%d"), Time.parse_utc("1963-11-23", "%Y-%m-%d")]
+    BafflingBirthdays.shared_birthday(birthdays).should be_false
+  end
+
+  pending "multiple birthdates without shared birthday" do
+    birthdays = [
+      Time.parse_utc("1966-07-29", "%Y-%m-%d"), Time.parse_utc("1977-02-12", "%Y-%m-%d"), Time.parse_utc("2001-12-25", "%Y-%m-%d"),
+      Time.parse_utc("1980-11-10", "%Y-%m-%d"),
+    ]
+    BafflingBirthdays.shared_birthday(birthdays).should be_false
+  end
+
+  pending "multiple birthdates with one shared birthday" do
+    birthdays = [
+      Time.parse_utc("1966-07-29", "%Y-%m-%d"), Time.parse_utc("1977-02-12", "%Y-%m-%d"), Time.parse_utc("2001-07-29", "%Y-%m-%d"),
+      Time.parse_utc("1980-11-10", "%Y-%m-%d"),
+    ]
+    BafflingBirthdays.shared_birthday(birthdays).should be_true
+  end
+
+  pending "multiple birthdates with more than one shared birthday" do
+    birthdays = [
+      Time.parse_utc("1966-07-29", "%Y-%m-%d"), Time.parse_utc("1977-02-12", "%Y-%m-%d"), Time.parse_utc("2001-12-25", "%Y-%m-%d"),
+      Time.parse_utc("1980-07-29", "%Y-%m-%d"), Time.parse_utc("2019-02-12", "%Y-%m-%d"),
+    ]
+    BafflingBirthdays.shared_birthday(birthdays).should be_true
+  end
+
+  pending "generate requested number of birthdates" do
+    (1..10).each do |size|
+      result = BafflingBirthdays.random_birthdates(size)
+      result.size.should eq(size)
+    end
+  end
+
+  pending "years are not leap years" do
+    result = BafflingBirthdays.random_birthdates(50)
+    result.all? { |date| Time.leap_year?(date.year) }.should be_false
+  end
+
+  pending "months are random" do
+    result = BafflingBirthdays.random_birthdates(100)
+    result.to_set { |date| date.month }.size.should eq(12)
+  end
+
+  pending "days are random" do
+    result = BafflingBirthdays.random_birthdates(300)
+    result.to_set { |date| date.day }.size.should eq(31)
+  end
+
+  pending "for one person" do
+    BafflingBirthdays.estimated_probability_of_shared_birthday(1).should be_close 0.0, 0.01
+  end
+
+  pending "among ten people" do
+    BafflingBirthdays.estimated_probability_of_shared_birthday(10).should be_close 11.694818, 1
+  end
+
+  pending "among twenty-three people" do
+    BafflingBirthdays.estimated_probability_of_shared_birthday(23).should be_close 50.729723, 1.5
+  end
+
+  pending "among seventy people" do
+    BafflingBirthdays.estimated_probability_of_shared_birthday(70).should be_close 99.915958, 1
+  end
+end
diff --git a/exercises/practice/baffling-birthdays/src/baffling_birthdays.cr b/exercises/practice/baffling-birthdays/src/baffling_birthdays.cr
new file mode 100644
index 00000000..cec8ad6c
--- /dev/null
+++ b/exercises/practice/baffling-birthdays/src/baffling_birthdays.cr
@@ -0,0 +1,12 @@
+class BafflingBirthdays
+  # Write your code for the 'BafflingBirthdays' exercise in this file.
+
+  def self.shared_birthday(birthdates : Array(Time)) : Bool
+  end
+
+  def self.random_birthdates(size : Int) : Array(Time)
+  end
+
+  def self.estimated_probability_of_shared_birthday(size : Int) : Float
+  end
+end

From 6d949ffd0f2af9b23f8ef3281e7978e2fdb114a7 Mon Sep 17 00:00:00 2001
From: meatball <meatballsofmeatballs@gmail.com>
Date: Fri, 2 Jan 2026 19:22:01 +0100
Subject: [PATCH 3/5] Format files

---
 exercises/practice/baffling-birthdays/.meta/src/example.cr | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exercises/practice/baffling-birthdays/.meta/src/example.cr b/exercises/practice/baffling-birthdays/.meta/src/example.cr
index a7bceb6d..4c75decc 100644
--- a/exercises/practice/baffling-birthdays/.meta/src/example.cr
+++ b/exercises/practice/baffling-birthdays/.meta/src/example.cr
@@ -24,6 +24,6 @@ class BafflingBirthdays
   end
 
   def self.estimated_probability_of_shared_birthday(size : Int) : Float
-    return (1..10000).sum {|_| shared_birthday(random_birthdates(size)) ? 1 : 0} / 100.0
+    return (1..10000).sum { |_| shared_birthday(random_birthdates(size)) ? 1 : 0 } / 100.0
   end
 end

From f77c54f7fea2dce4004543a415627d5bbf9945bd Mon Sep 17 00:00:00 2001
From: meatball <meatballsofmeatballs@gmail.com>
Date: Fri, 2 Jan 2026 19:52:10 +0100
Subject: [PATCH 4/5] Fix when suppose to generate for 23 people

---
 exercises/practice/baffling-birthdays/.meta/src/example.cr    | 2 +-
 exercises/practice/baffling-birthdays/.meta/test_template.ecr | 2 +-
 .../baffling-birthdays/spec/baffling_birthdays_spec.cr        | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/exercises/practice/baffling-birthdays/.meta/src/example.cr b/exercises/practice/baffling-birthdays/.meta/src/example.cr
index 4c75decc..629ea271 100644
--- a/exercises/practice/baffling-birthdays/.meta/src/example.cr
+++ b/exercises/practice/baffling-birthdays/.meta/src/example.cr
@@ -16,7 +16,7 @@ class BafflingBirthdays
   def self.random_birthdates(size : Int) : Array(Time)
     result = [] of Time
     size.times do |_|
-      time = Time.utc(2025, 1, 1).shift days: Random.rand(356)
+      time = Time.utc(2025, 1, 1).shift days: Random.rand(364)
       result << time
     end
 
diff --git a/exercises/practice/baffling-birthdays/.meta/test_template.ecr b/exercises/practice/baffling-birthdays/.meta/test_template.ecr
index 59612a17..84f3d62e 100644
--- a/exercises/practice/baffling-birthdays/.meta/test_template.ecr
+++ b/exercises/practice/baffling-birthdays/.meta/test_template.ecr
@@ -9,7 +9,7 @@ describe "<%-= to_capitalized(@json["exercise"].to_s) %>" do
             birthdays = [<%= sub_case["input"]["birthdates"].as_a.map {|date| "Time.parse_utc(\"#{date}\",  \"%Y-%m-%d\")" }.join(", ") %>]
             <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(birthdays).should be_<%= sub_case["expected"] %>
         <%- elsif sub_case["property"] == "estimatedProbabilityOfSharedBirthday" -%>
-            <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(<%= sub_case["input"]["groupSize"] %>).should be_close <%= (sub_case["expected"]) %>, <%= sub_case["input"]["groupSize"].as_i == 23 ? 1.5 : sub_case["input"]["groupSize"].as_i == 1 ? 0.01 : 1  %>
+            <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(<%= sub_case["input"]["groupSize"] %>).should be_close <%= (sub_case["expected"]) %>, <%= sub_case["input"]["groupSize"].as_i == 1 ? 0.01 : 1  %>
         <%- elsif sub_case["expected"] == "length == groupsize" -%>
             (1..10).each do |size|
                 result = <%= to_capitalized(@json["exercise"].to_s) %>.<%= sub_case["property"].to_s.underscore %>(size)
diff --git a/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
index 45ffc50f..ae858cf0 100644
--- a/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
+++ b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
@@ -86,8 +86,8 @@ describe "BafflingBirthdays" do
     BafflingBirthdays.estimated_probability_of_shared_birthday(10).should be_close 11.694818, 1
   end
 
-  pending "among twenty-three people" do
-    BafflingBirthdays.estimated_probability_of_shared_birthday(23).should be_close 50.729723, 1.5
+  it "among twenty-three people" do
+    BafflingBirthdays.estimated_probability_of_shared_birthday(23).should be_close 50.729723, 1
   end
 
   pending "among seventy people" do

From dff34d2bb73c9b58bfd4c3c9e2dee878e928f745 Mon Sep 17 00:00:00 2001
From: meatball <meatballsofmeatballs@gmail.com>
Date: Fri, 2 Jan 2026 19:57:03 +0100
Subject: [PATCH 5/5] 2nd attempt

---
 exercises/practice/baffling-birthdays/.meta/src/example.cr      | 2 +-
 .../practice/baffling-birthdays/spec/baffling_birthdays_spec.cr | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/exercises/practice/baffling-birthdays/.meta/src/example.cr b/exercises/practice/baffling-birthdays/.meta/src/example.cr
index 629ea271..f8dd98f8 100644
--- a/exercises/practice/baffling-birthdays/.meta/src/example.cr
+++ b/exercises/practice/baffling-birthdays/.meta/src/example.cr
@@ -16,7 +16,7 @@ class BafflingBirthdays
   def self.random_birthdates(size : Int) : Array(Time)
     result = [] of Time
     size.times do |_|
-      time = Time.utc(2025, 1, 1).shift days: Random.rand(364)
+      time = Time.utc(2025, 1, 1).shift days: Random.rand(365)
       result << time
     end
 
diff --git a/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
index ae858cf0..64b57264 100644
--- a/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
+++ b/exercises/practice/baffling-birthdays/spec/baffling_birthdays_spec.cr
@@ -86,7 +86,7 @@ describe "BafflingBirthdays" do
     BafflingBirthdays.estimated_probability_of_shared_birthday(10).should be_close 11.694818, 1
   end
 
-  it "among twenty-three people" do
+  pending "among twenty-three people" do
     BafflingBirthdays.estimated_probability_of_shared_birthday(23).should be_close 50.729723, 1
   end