negabinary.cpp

puzzles/interviews/training/negabinary.cpp

@@ -0,0 +1,61 @@
+/*
+VIM: let b:lcppflags="-std=c++2a -O2 -pthread -I."
+VIM: let b:wcppflags="/O2 /EHsc /DWIN32"
+VIM-: let b:argv=""
+*/
+#include <iostream>
+#include <exception>
+#include <chrono>
+#include <type_traits>
+#include <iomanip>
+
+
+template <typename T>
+constexpr T negabinary(T v){
+    static_assert(std::is_integral_v<T>, "Only integral types expected.");
+    const T base = -2;
+    const T abs_base = abs(base);
+    std::make_unsigned_t<T> n = 0;
+    int i = 0;
+    while ( v ){
+        T r = v % base;
+        v /= base;
+        if ( r < 0){
+            v +=1;
+            r = abs_base - r;
+        }
+        n |= std::make_unsigned_t<T>(r) << i;
+        ++i;
+    }
+    return n;
+}
+
+
+int main ( void )
+{try{
+    auto begin = std::chrono::high_resolution_clock::now();
+
+
+    for (int i = -16; i < 17; ++i){
+        std::cout << std::setbase(10) << i << " == " << std::setbase(16) << std::showbase << negabinary(i) << std::endl;
+    }
+    //std::cout << negabinary(2.) << std::endl;
+
+    auto end = std::chrono::high_resolution_clock::now();
+    std::chrono::duration<double> seconds = end - begin;
+    std::cout << "Time: " << seconds.count() << std::endl;
+    return 0;
+}
+catch ( const std::exception& e )
+{
+    std::cerr << std::endl
+            << "std::exception(\"" << e.what() << "\")." << std::endl;
+    return 2;
+}
+catch ( ... )
+{
+    std::cerr  << std::endl
+            << "unknown exception." << std::endl;
+    return 1;
+}}
+