commit 2eb04509db71b65da6ef0a151e661cb0c5dd8b7d
Author: Douwe Ravers <douwe.ravers@douwco.be>
Date:   Fri Aug 7 13:29:57 2026 +0200

    Added previous arduino implementations.

diff --git a/EulerProject.ino b/EulerProject.ino
new file mode 100644
index 0000000..b4e019d
--- /dev/null
+++ b/EulerProject.ino
@@ -0,0 +1,24 @@
+#include "Timer.h"
+
+#include "ProblemBase.hpp"
+#include "Problem3.hpp"
+
+Problem3 problem = Problem3();
+Timer timer(MICROS);
+// Initialize serial connection
+void setup() {
+  Serial.begin(9600);
+  Serial.println("Start calculating...");
+  timer.start();  // start the timer
+}
+
+// Calculation loop
+void loop() {
+  if (problem.Step()) {
+    // Print solution
+    Serial.println("Result = " + String(problem.output) + " in " + String(timer.read()) + "us");
+    timer.stop();
+    delay(100);
+    exit(0);
+  }
+}
\ No newline at end of file
diff --git a/Problem1.cpp b/Problem1.cpp
new file mode 100644
index 0000000..3876d00
--- /dev/null
+++ b/Problem1.cpp
@@ -0,0 +1,21 @@
+#include "Problem1.hpp"
+
+Problem1::Problem1() {
+  input = 1000;
+}
+
+bool Problem1::Step() {
+  // add all factors of 3 under input
+  factor3 += 3;
+  if (factor3 < input) output += factor3;
+
+  // add all factors of 5 under input but skip factors of 3
+  factor5 += 5;
+  if (factor5 < input) {
+    factor5_tick++;
+    if (factor5_tick != 3) output += factor5;
+    else factor5_tick = 0;
+  }
+
+  return input < factor3 && input < factor5;
+}
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diff --git a/Problem1.hpp b/Problem1.hpp
new file mode 100644
index 0000000..fb37c08
--- /dev/null
+++ b/Problem1.hpp
@@ -0,0 +1,18 @@
+#ifndef Problem1_h
+#define Problem1_h
+
+#include "ProblemBase.hpp"
+
+class Problem1 : public ProblemBase {
+
+private:
+  unsigned long factor3 = 0;
+  unsigned long factor5 = 0;
+  unsigned long factor5_tick = 0;
+
+public:
+  Problem1();
+  bool Step();
+};
+
+#endif
\ No newline at end of file
diff --git a/Problem2.cpp b/Problem2.cpp
new file mode 100644
index 0000000..01fecbf
--- /dev/null
+++ b/Problem2.cpp
@@ -0,0 +1,19 @@
+#include "Problem2.hpp"
+#include "Arduino.h"
+
+Problem2::Problem2() {
+  input = 4000000;
+}
+
+bool Problem2::Step() {
+  // Sum fibonacci values
+  if ((fibonacci & 0b1) == 0) output += fibonacci;
+
+  // calculate next fibonacci value
+  fibonacci = value1 + value2;
+  value1 = value2;
+  value2 = fibonacci;
+
+  // stop if fibonacci value over max
+  return input < fibonacci;
+}
\ No newline at end of file
diff --git a/Problem2.hpp b/Problem2.hpp
new file mode 100644
index 0000000..636e4a3
--- /dev/null
+++ b/Problem2.hpp
@@ -0,0 +1,18 @@
+#ifndef Problem2_h
+#define Problem2_h
+
+#include "ProblemBase.hpp"
+
+class Problem2 : public ProblemBase {
+
+private:
+  unsigned long value1 = 0;
+  unsigned long value2 = 1;
+  unsigned long fibonacci;
+
+public:
+  Problem2();
+  bool Step();
+};
+
+#endif
\ No newline at end of file
diff --git a/Problem3.cpp b/Problem3.cpp
new file mode 100644
index 0000000..cc6d316
--- /dev/null
+++ b/Problem3.cpp
@@ -0,0 +1,41 @@
+#include "WString.h"
+#include "HardwareSerial.h"
+#include "Problem3.hpp"
+#include "Arduino.h"
+#include "Vector.h"
+
+Problem3::Problem3() {
+  fl_input = 600851475143;
+
+  unsigned long primeArray[] = { 2 };
+  primes = Vector<unsigned long>(primeArray, 1);
+}
+
+bool Problem3::Step() {
+  Serial.println("iterator = " + String(iterator));
+  // Find prime
+  bool isPrime;
+  Serial.println("known primes = " + String(primes.size()));
+
+  for (unsigned long prime : primes) {
+    Serial.println("prime = " + String(prime));
+    isPrime = iterator % prime != 0;
+    if (!isPrime) break;
+  }
+
+  // Current value is new prime
+  if (isPrime) {
+    primes.push_back(iterator);
+    Serial.println("Found prime = " + String(iterator));
+    // Is number factor of input
+    if (fl_input / iterator == floor(fl_input / iterator)) {
+      // Save current prime as biggest prime and promote other factor as new max.
+      Serial.println("Found prime factor = " + String(iterator));
+      output = iterator;
+      fl_input = fl_input / iterator;
+    }
+  }
+  iterator++;
+  delay(1000);
+  return fl_input < iterator;
+}
\ No newline at end of file
diff --git a/Problem3.hpp b/Problem3.hpp
new file mode 100644
index 0000000..5c3e1c4
--- /dev/null
+++ b/Problem3.hpp
@@ -0,0 +1,19 @@
+#ifndef Problem3_h
+#define Problem3_h
+
+#include "ProblemBase.hpp"
+#include "Vector.h"
+
+class Problem3 : public ProblemBase {
+
+private:
+  Vector<unsigned long> primes;
+  unsigned long iterator = 2;
+  float fl_input;
+  
+public:
+  Problem3();
+  bool Step();
+};
+
+#endif
\ No newline at end of file
diff --git a/ProblemBase.hpp b/ProblemBase.hpp
new file mode 100644
index 0000000..3e3dbe6
--- /dev/null
+++ b/ProblemBase.hpp
@@ -0,0 +1,16 @@
+#ifndef ProblemBase_h
+#define ProblemBase_h
+
+class ProblemBase {
+
+public:
+  unsigned long output;
+
+protected:
+  unsigned long input;
+
+public:
+  virtual bool Step();
+};
+
+#endif
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..c9115ab
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# ProjectEuler
+My source code for project Euler solutions
+Extra challenge: All algorithms are run on an Arduino