add: 230302-CN

cpp/2303/230302-CN.cpp

@@ -0,0 +1,31 @@
+#include <string>
+#include <iostream>
+
+/**
+ * 面试题 05.02. Binary Number to String LCCI
+ *
+ * Given a real number between 0 and 1 (e.g., 0.72) that is passed in as a double, print the binary representation. If the number cannot be represented accurately in binary with at most 32 characters, print "ERROR".
+ */
+
+class Solution {
+public:
+	static std::string printBin(const double n) {
+		const auto b = *reinterpret_cast<const unsigned long long*>(&n);
+		const auto d = 1023 - ((b >> 52) & 0x7FF);
+		const auto e = b & 0x000FFFFFFFFFFFFF;
+
+		const auto mask = (1ULL << (52 - (31 - d))) - 1;
+		if (e & mask)
+			return "ERROR";
+		auto ret = std::string("0.").append(d - 1, '0').append(1, '1');
+		for (int i = 0; i < 31 - d; ++i)
+			ret.push_back(((1ULL << (51 - i)) & e) ? '1' : '0');
+		for (; '0' == ret.back(); ret.pop_back());
+		return ret;
+	}
+};
+
+int main() {
+	std::cout << Solution::printBin(0.1);
+	return 0;
+}

cpp/2303/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2303)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2303 230301-CN.cpp)
+ADD_EXECUTABLE(2303 230302-CN.cpp)