diff --git a/cpp/2304/230406-CN.cpp b/cpp/2304/230406-CN.cpp
new file mode 100644
index 0000000..28196ee
--- /dev/null
+++ b/cpp/2304/230406-CN.cpp
@@ -0,0 +1,87 @@
+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+class SolutionConstruct {
+private:
+	static inline std::string toStr(int n) {
+		int i = 31;
+		for (; i >= 0 && !(n & (1 << i)); --i);
+		std::string ret(i + 1, '0');
+		for (int j = i; j >= 0; --j)
+			if (n & (1 << j))
+				ret[i - j] = '1';
+		return ret.empty() ? "0" : ret;
+	}
+
+	static inline int toInt(const std::string& s) {
+		auto ret = 0, i = 1;
+		for (auto it = s.rbegin(); it != s.rend(); ++it) {
+			ret |= (*it & 1) ? i : 0;
+			i <<= 1;
+		}
+		return ret;
+	}
+
+	static constexpr inline int eval(int n) { return (n & 0x55555555) - (n & 0xAAAAAAAA); }
+
+	static const inline std::string L5[] = {"0", "1", "110", "111", "100", "101"};
+
+	static const inline std::string v[] = {"01", "00", "11", "10"};
+
+public:
+	static std::string baseNeg2(int n) {
+		if (n <= 5)
+			return L5[n];
+		int cur, prev = 5, i = 4;
+		for (; n > (cur = prev + (1 << i)); (prev = cur), (i += 2));
+		auto ret = std::string(1, '0' | (n & 1));
+		for (int x = (n - prev - 1) >> 1, j = 1; j < (i >> 1); (x >>= 2), ++j)
+			ret = v[x & 3] + ret;
+		return v[(n - prev > (cur - prev) / 2) + 2] + ret;
+	}
+
+	static void test(int n) {
+		for (int i = 0; i < n; ++i) {
+			int x = eval(i);
+			if (x < 0)
+				continue;
+			if (i != toInt(baseNeg2(x)))
+				std::printf("%d Bad!!\n", x);
+		}
+	}
+};
+
+/**
+ * 1017. Convert to Base -2
+ *
+ * Given an integer n, return a binary string representing its representation in base -2.
+ * Note that the returned string should not have leading zeros unless the string is "0".
+ */
+
+class Solution {
+private:
+	static const inline std::string L5[] = {"0", "1", "110", "111", "100", "101"};
+
+	static const inline std::string v[] = {"01", "00", "11", "10"};
+
+public:
+	static std::string baseNeg2(int n) {
+		if (n <= 5)
+			return L5[n];
+		int cur, prev = 5, i = 4;
+		for (; n > (cur = prev + (1 << i)); (prev = cur), (i += 2));
+		auto ret = std::string(1, '0' | (n & 1));
+		for (int x = (n - prev - 1) >> 1, j = 1; j < (i >> 1); (x >>= 2), ++j)
+			ret = v[x & 3] + ret;
+		return v[(n - prev > (cur - prev) / 2) + 2] + ret;
+	}
+};
+
+int main() {
+	SolutionConstruct::test(0x1000000);
+	// std::cout << Solution::baseNeg2(77);
+	return 0;
+}
diff --git a/cpp/2304/CMakeLists.txt b/cpp/2304/CMakeLists.txt
index 698b748..bac0374 100644
--- a/cpp/2304/CMakeLists.txt
+++ b/cpp/2304/CMakeLists.txt
@@ -4,4 +4,4 @@ PROJECT(2304)
 SET(CMAKE_CXX_STANDARD 23)
 SET(CMAKE_EXPORT_COMPILE_COMMANDS true)
 
-ADD_EXECUTABLE(2304 230405.cpp)
+ADD_EXECUTABLE(2304 230406-CN.cpp)