add solution 3 and start of 4

README.md

@@ -13,3 +13,5 @@ Find the sum of all the multiples of 3 or 5 below 1000.
 Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
 1, 2, 3, 5, 8, 13, 21, 34, 55, 89,
 By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
+
+# Euler problem 3 :

euler/euler/euler.cpp

@@ -5,6 +5,8 @@
 #include <cassert> 
 #include "euler_p1.h"
 #include "euler_p2.h"
+#include "euler_p3.h"
+#include "euler_p4.h"
 
 
 
@@ -12,6 +14,8 @@ void unit_tests() {
 
     assert(euler1(10) == 23);
     assert(euler2(10) == 10);
+    assert(euler3(13195) == 29);
+    assert(euler4(99,99) == 9009);
 
     std::cout << "All tests passed! continues main." << std::endl;
 }
@@ -26,11 +30,21 @@ int euler_p2() {
     return res;
 }
 
+long long int euler_p3() {
+    long long int res = euler3(600851475143);
+    return res;
+}
+
+int euler_p4() {
+    int res = euler4(999, 999);
+}
+
 int main()
 {
     unit_tests();
     
     std::cout << "the result for problem 1 = " << euler_p1() << std::endl;
     std::cout << "the result for problem 2 = " << euler_p2() << std::endl;
+    std::cout << "the result for problem 3 = " << euler_p3() << std::endl;
 }
 

euler/euler/euler.vcxproj

@@ -130,10 +130,14 @@
     <ClCompile Include="euler.cpp" />
     <ClCompile Include="euler_p1.cpp" />
     <ClCompile Include="euler_p2.cpp" />
+    <ClCompile Include="euler_p3.cpp" />
+    <ClCompile Include="euler_p4.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="euler_p1.h" />
     <ClInclude Include="euler_p2.h" />
+    <ClInclude Include="euler_p3.h" />
+    <ClInclude Include="euler_p4.h" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">

euler/euler/euler.vcxproj.filters

@@ -24,6 +24,12 @@
     <ClCompile Include="euler_p2.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="euler_p3.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="euler_p4.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="euler_p1.h">
@@ -32,5 +38,11 @@
     <ClInclude Include="euler_p2.h">
       <Filter>Source Files</Filter>
     </ClInclude>
+    <ClInclude Include="euler_p3.h">
+      <Filter>Source Files</Filter>
+    </ClInclude>
+    <ClInclude Include="euler_p4.h">
+      <Filter>Source Files</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>

euler/euler/euler_p2.h

@@ -1,5 +1,4 @@
 #pragma once
-#pragma once
 /**
  * @brief Solves Euler problem 2: Even Fibonacci Numbers
  *

euler/euler/euler_p3.cpp

@@ -0,0 +1,30 @@
+#include "euler_p3.h"
+#include <vector>
+
+
+/*
+The prime factors of 13195 are 5, 7, 13 and 29
+What is the largest prime factor of the number 600851475143
+*/
+
+long long int euler3(long long int limit) {
+    long long int largest_factor = 0;
+
+    
+    while (limit % 2 == 0) {
+        largest_factor = 2;
+        limit /= 2;
+    }
+    for (long long int i = 3; i <= sqrt(limit); i += 2) {
+        while (limit % i == 0) {
+            largest_factor = i;
+            limit /= i;
+        }
+    }
+
+    if (limit > 2) {
+        largest_factor = limit;
+    }
+
+    return largest_factor;
+}

euler/euler/euler_p3.h

@@ -0,0 +1,12 @@
+#pragma once
+/**
+ * @brief Solves Euler problem 3: Largest prime factor
+ *
+ * This function calculates the highest prime number that devides the given limit
+ *
+ * @param limit The upper limit for the range to consider (should be positive).
+ * @return The highest prime lower or equal to the limit.
+ *
+ * @note This function only works with positive integer inputs.
+ */
+long long int euler3(long long int limit);

euler/euler/euler_p4.cpp

@@ -0,0 +1,11 @@
+#include "euler_p4.h"
+#include <string>
+
+int euler4() {
+	return 1001;
+}
+
+bool isPalindrome(const std::string& testString) {
+	
+	return true;
+}

euler/euler/euler_p4.h

@@ -0,0 +1,13 @@
+#pragma once
+/**
+ * @brief Solves Euler problem 4: largest palindrome
+ *
+ * This function calculates the largest palindrome that is the result of two numbers
+ *
+ * @param limitA one of the numbers to use in the multiplication
+ * @param limitB one of the numbers to use in the multiplication
+ * @return The highest palindrome resulting from a combination a & b 
+ *
+ * @note This function only works with positive integer inputs.
+ */
+int euler4(int limitA, int limitB);