diff --git a/cpp/2304/230409.cpp b/cpp/2304/230409.cpp
new file mode 100644
index 0000000..48ee4a5
--- /dev/null
+++ b/cpp/2304/230409.cpp
@@ -0,0 +1,88 @@
+#include <string>
+#include <vector>
+#include <functional>
+#include <iostream>
+
+struct Info {
+	int cnt[26]{};
+	bool has_value = false;
+	bool is_bad = false;
+	bool in_loop = false;
+
+	Info& operator&=(const Info& rhs) {
+		for (int i = 0; i < 26; ++i)
+			this->cnt[i] = std::max(this->cnt[i], rhs.cnt[i]);
+		return *this;
+	}
+
+	int get() const {
+		int ret = cnt[0];
+		for (int i = 1; i < 26; ++i)
+			ret = std::max(ret, cnt[i]);
+		return ret;
+	}
+
+};
+
+/**
+ * 1857. Largest Color Value in a Directed Graph
+ *
+ * There is a directed graph of n colored nodes and m edges. The nodes are numbered from 0 to n - 1.
+ * You are given a string colors where colors[i] is a lowercase English letter representing the color of the ith node in this graph (0-indexed). You are also given a 2D array edges where edges[j] = [aj, bj] indicates that there is a directed edge from node aj to node bj.
+ * A valid path in the graph is a sequence of nodes x1 -> x2 -> x3 -> ... -> xk such that there is a directed edge from xi to xi+1 for every 1 <= i < k. The color value of the path is the number of nodes that are colored the most frequently occurring color along that path.
+ * Return the largest color value of any valid path in the given graph, or -1 if the graph contains a cycle.
+ */
+
+class Solution {
+public:
+	static int largestPathValue(const std::string&, const std::vector<std::vector<int>>&);
+};
+
+int Solution::largestPathValue(const std::string& colors, const std::vector<std::vector<int>>& edges) {
+	const int m = edges.size(), n = colors.length();
+	std::vector<std::vector<int>> G(n);
+	for (auto&& e : edges)
+		G[e[0]].push_back(e[1]);
+	std::vector<Info> dp(n);
+	std::function<const Info&(int)> d = [&](int idx) -> const Info& {
+		auto& ans = dp[idx];
+		if (ans.has_value)
+			return ans;
+		if (ans.in_loop) {
+			ans.is_bad = true;
+			return ans;
+		} else if (G[idx].empty()) {
+			ans.cnt[colors[idx] - 'a'] = 1;
+			ans.has_value = true;
+			return ans;
+		}
+		ans.in_loop = true;
+		for (int nx : G[idx]) {
+			const auto& nxd = d(nx);
+			if (nxd.is_bad) {
+				ans.is_bad = true;
+				return ans;
+			}
+			ans &= nxd;
+		}
+		++ans.cnt[colors[idx] - 'a'];
+		ans.has_value = true;
+		ans.in_loop = false;
+		return ans;
+	};
+	int ans = -1;
+	for (int i = 0; i < n; ++i) {
+		const auto& c = d(i);
+		if (c.is_bad)
+			return -1;
+		ans = std::max(ans, c.get());
+	}
+	return ans;
+}
+
+int main() {
+	std::cout << Solution::largestPathValue("hhqhuqhqff", {
+		{0,1},{0,2},{2,3},{3,4},{3,5},{5,6},{2,7},{6,7},{7,8},{3,8},{5,8},{8,9},{3,9},{6,9}
+	});
+	return 0;
+}
diff --git a/cpp/2304/CMakeLists.txt b/cpp/2304/CMakeLists.txt
index a1a839d..19b9e5a 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 230409-CN.cpp)
+ADD_EXECUTABLE(2304 230409.cpp)