From 1ff709e7bdaeb0d325fa789a150e4b1c357751ea Mon Sep 17 00:00:00 2001
From: ddaniel27 <danieldorado27@gmail.com>
Date: Mon, 6 May 2024 22:13:25 -0500
Subject: [PATCH 1/3] [Solution] Project euler challenge 19 with tests

---
 Project-Euler/Problem019.js           | 55 +++++++++++++++++++++++++++
 Project-Euler/test/Problem019.test.js |  8 ++++
 2 files changed, 63 insertions(+)
 create mode 100644 Project-Euler/Problem019.js
 create mode 100644 Project-Euler/test/Problem019.test.js

diff --git a/Project-Euler/Problem019.js b/Project-Euler/Problem019.js
new file mode 100644
index 0000000000..6b273b5953
--- /dev/null
+++ b/Project-Euler/Problem019.js
@@ -0,0 +1,55 @@
+/**
+ * Problem 19 - Counting Sundays
+ *
+ * @see {@link https://projecteuler.net/problem=19}
+ *
+ * You are given the following information, but you may prefer to do some research for yourself.
+ * 1 Jan 1900 was a Monday.
+ * Thirty days has September,
+ * April, June and November.
+ * All the rest have thirty-one,
+ * Saving February alone,
+ * Which has twenty-eight, rain or shine.
+ * And on leap years, twenty-nine.
+ * A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
+ * How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?
+ *
+ * @author ddaniel27
+ */
+
+// Check if a year is a leap year
+// A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
+function isLeapYear(year) {
+  return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0
+}
+
+function problem19() {
+  let sundaysCount = 0 // Count of Sundays
+  let dayOfWeek = 2 // 1st Jan 1900 was a Monday, so 1st Jan 1901 was a Tuesday
+
+  for (let year = 1901; year <= 2000; year++) {
+    // From 1901 to 2000
+    for (let month = 1; month <= 12; month++) {
+      // From January to December
+      if (dayOfWeek === 0) {
+        // If it's a Sunday (0 is Sunday, 1 is Monday, ..., 6 is Saturday)
+        sundaysCount++
+      }
+
+      let daysInMonth = 31
+      if (month === 4 || month === 6 || month === 9 || month === 11) {
+        // April, June, September, November
+        daysInMonth = 30
+      } else if (month === 2) {
+        // February
+        daysInMonth = isLeapYear(year) ? 29 : 28
+      }
+
+      dayOfWeek = (dayOfWeek + daysInMonth) % 7 // Calculate the day of the week
+    }
+  }
+
+  return sundaysCount
+}
+
+export { problem19 }
diff --git a/Project-Euler/test/Problem019.test.js b/Project-Euler/test/Problem019.test.js
new file mode 100644
index 0000000000..8845e5a0ac
--- /dev/null
+++ b/Project-Euler/test/Problem019.test.js
@@ -0,0 +1,8 @@
+import { problem19 } from '../Problem019.js'
+
+describe('checking sundays during the twentieth century', () => {
+  // Project Euler Challenge Check
+  test('result should be 171', () => {
+    expect(problem19()).toBe(171)
+  })
+})

From 664da39d784ad0e0c90a960b0dbd576acab32bfc Mon Sep 17 00:00:00 2001
From: ddaniel27 <danieldorado27@gmail.com>
Date: Mon, 27 May 2024 10:27:29 -0500
Subject: [PATCH 2/3] update leap year function

---
 Project-Euler/Problem019.js | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/Project-Euler/Problem019.js b/Project-Euler/Problem019.js
index 6b273b5953..75e8d7528b 100644
--- a/Project-Euler/Problem019.js
+++ b/Project-Euler/Problem019.js
@@ -16,12 +16,7 @@
  *
  * @author ddaniel27
  */
-
-// Check if a year is a leap year
-// A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
-function isLeapYear(year) {
-  return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0
-}
+import { isLeapYear } from '../Maths/LeapYear'
 
 function problem19() {
   let sundaysCount = 0 // Count of Sundays

From 98a6fa4d80127096fbc82d821e70158b2e9dc638 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lars=20M=C3=BCller?=
 <34514239+appgurueu@users.noreply.github.com>
Date: Sat, 15 Jun 2024 00:18:31 +0200
Subject: [PATCH 3/3] Remove unnecessary, confusingly placed comments

---
 Project-Euler/Problem019.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Project-Euler/Problem019.js b/Project-Euler/Problem019.js
index 75e8d7528b..5b488c7f96 100644
--- a/Project-Euler/Problem019.js
+++ b/Project-Euler/Problem019.js
@@ -23,9 +23,7 @@ function problem19() {
   let dayOfWeek = 2 // 1st Jan 1900 was a Monday, so 1st Jan 1901 was a Tuesday
 
   for (let year = 1901; year <= 2000; year++) {
-    // From 1901 to 2000
     for (let month = 1; month <= 12; month++) {
-      // From January to December
       if (dayOfWeek === 0) {
         // If it's a Sunday (0 is Sunday, 1 is Monday, ..., 6 is Saturday)
         sundaysCount++