diff --git a/cpp/2303/230327-CN.cpp b/cpp/2303/230327-CN.cpp
new file mode 100644
index 0000000..e113f63
--- /dev/null
+++ b/cpp/2303/230327-CN.cpp
@@ -0,0 +1,34 @@
+#include <string>
+
+/**
+ * 1638. Count Substrings That Differ by One Character
+ *
+ * Given two strings s and t, find the number of ways you can choose a non-empty substring of s and replace a single character by a different character such that the resulting substring is a substring of t. In other words, find the number of substrings in s that differ from some substring in t by exactly one character.
+ * For example, the underlined substrings in "computer" and "computation" only differ by the 'e'/'a', so this is a valid way.
+ * Return the number of substrings that satisfy the condition above.
+ * A substring is a contiguous sequence of characters within a string.
+ */
+
+class Solution {
+public:
+	static int countSubstrings(const std::string& s, const std::string& t) {
+		const int m = s.length(), n = t.length();
+		auto count = [m, n, &s, &t](int x, int y) {
+			bool cap = false;
+			int cnt = 0;
+			for (int i = x, j = y; i < m && j < n; ++i, ++j) {
+				if (s[i] != t[j]) {
+					if (cap) break;
+					else cap = true;
+				}
+				if (cap) ++cnt;
+			}
+			return cnt;
+		};
+		int ans = 0;
+		for (int i = 0; i < m; ++i)
+			for (int j = 0; j < n; ++j)
+				ans += count(i, j);
+		return ans;
+	}
+};
diff --git a/cpp/2303/CMakeLists.txt b/cpp/2303/CMakeLists.txt
index ca81fac..645f57d 100644
--- a/cpp/2303/CMakeLists.txt
+++ b/cpp/2303/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2303)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2303 230326-CN.cpp)
+ADD_EXECUTABLE(2303 230327-CN.cpp)