- Added solutions by Ulrich Rieke.

1 files changed, 50 insertions, 0 deletions

diff --git a/challenge-149/ulrich-rieke/cpp/ch-2.cpp b/challenge-149/ulrich-rieke/cpp/ch-2.cpp
new file mode 100644
index 0000000000..abc278d886
--- /dev/null
+++ b/challenge-149/ulrich-rieke/cpp/ch-2.cpp
@@ -0,0 +1,50 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+#include <cstdlib>
+#include <cmath>
+#include <iterator>
+
+long parseBase( std::string numberstring , int base ) {
+  static std::string allBases {"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"} ;
+  long base10 = 0 ;
+  long current = 1 ;
+  auto start { allBases.begin( ) } ;
+  std::reverse( numberstring.begin( ) , numberstring.end( ) ) ;
+  for ( auto c : numberstring ) {
+      auto found = std::find( allBases.begin( ) , allBases.end( ) , c ) ;
+      long steps = static_cast<long>( std::distance(start , found )) ;
+      base10 += steps * current ;
+      current *= base ;
+  }
+  return base10 ;
+}
+
+bool isPerfectSquare( long number ) {
+  long double root = sqrtl( static_cast<long double>( number ) ) ;
+  return ( floorl( root ) == root ) ;
+}
+
+
+int main( int argc, char * argv[0] ) {
+  int n = std::atoi( argv[1] ) ;
+  std::string allBases {"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"} ;
+  std::string selection { allBases.substr( 0 , n ) } ;
+  reverse( selection.begin( ) , selection.end( ) ) ;
+  bool found = false ;
+  do {
+      long theNumber = 0 ;
+      if ( n == 10 )
+    theNumber = std::stoul( selection ) ;
+      else
+    theNumber = parseBase( selection , n ) ;
+      if ( isPerfectSquare( theNumber ) ) {
+    std::cout << selection << std::endl ;
+    found = true ;
+    break ;
+      }
+  } while ( std::prev_permutation( selection.begin( ) , selection.end( ) )) ;
+  if ( found == false )
+      std::cout << "no perfect square in base " << n << " was found!\n" ;
+  return 0 ;
+}