1 files changed, 76 insertions, 0 deletions
diff --git a/challenge-150/ulrich-rieke/cpp/ch-2.cpp b/challenge-150/ulrich-rieke/cpp/ch-2.cpp
new file mode 100644
index 0000000000..db49e43808
--- /dev/null
+++ b/challenge-150/ulrich-rieke/cpp/ch-2.cpp
@@ -0,0 +1,76 @@
+#include <iostream>
+#include <vector>
+#include <set>
+#include <cmath>
+
+bool isPrime( int i ) {
+  if ( i == 1 )
+      return false ;
+  else {
+      int stop = std::sqrt( static_cast<double>( i ) ) ;
+      for ( int d = 2 ; d <= stop ; d++ )
+    if ( i % d == 0 )
+        return false ;
+      return true ;
+  }
+}
+
+std::vector<int> findDivisors( int n ) {
+  std::vector<int> divisors ;
+  for ( int i = 1 ; i < n + 1 ; i++ ) {
+      if ( n % 1 == 0 )
+    divisors.push_back( i ) ;
+  }
+  return divisors ;
+}
+
+std::vector<int> primeFactorialize( int n ) {
+  std::vector<int> primeDecomposition ;
+  std::vector<int> divisors = findDivisors( n ) ;
+  std::vector<int> primeFactors ;
+  for ( int i : divisors ) {
+      if ( isPrime( i ) )
+    primeFactors.push_back( i ) ;
+  }
+  int num = 0 ;
+  while ( n != 1 ) {
+      int nextFactor = primeFactors[ num ] ;
+      while ( n % nextFactor == 0 ) {
+    primeDecomposition.push_back( nextFactor ) ;
+    n /= nextFactor ;
+      }
+      if ( num + 1 < primeFactors.size( ) )
+    num++ ;
+  }
+  return primeDecomposition ;
+}
+
+bool isSquareFree( int n ) {
+  if ( n == 1 ) {
+      return true ;
+  }
+  else {
+      std::vector<int> primeFactors = primeFactorialize( n ) ;
+      std::set<int> numset( primeFactors.begin( ) , primeFactors.end( ) ) ;
+      return primeFactors.size( ) == numset.size( ) ;
+  }
+}
+
+int main( ) {
+  std::vector<int> squareFrees ;
+  int current = 1 ;
+  while ( current < 501 ) {
+      if ( isSquareFree( current ) )
+    squareFrees.push_back( current ) ;
+      current++ ;
+  }
+  int count = 1 ;
+  for ( int i : squareFrees ) {
+      std::cout << i << " " ;
+      count++ ;
+      if ( count % 15 == 0 )//improves the output slightly
+    std::cout << std::endl ;
+  }
+  std::cout << std::endl ;
+  return 0 ;
+}