diff --git a/cpp/2206/220615.cpp b/cpp/2206/220615.cpp
new file mode 100644
index 0000000..51e2208
--- /dev/null
+++ b/cpp/2206/220615.cpp
@@ -0,0 +1,69 @@
+#include <utility>
+#include <queue>
+#include <vector>
+#include <string>
+#include <iostream>
+#include <tuple>
+#include <functional>
+
+/**
+ * 1048. Longest String Chain
+ * You are given an array of words where each word consists of lowercase English letters.
+ * wordA is a predecessor of wordB if and only if we can insert exactly one letter anywhere in wordA without changing the order of the other characters to make it equal to wordB.
+ * For example, "abc" is a predecessor of "abac", while "cba" is not a predecessor of "bcad".
+ * A word chain is a sequence of words [word1, word2, ..., wordk] with k >= 1, where word1 is a predecessor of word2, word2 is a predecessor of word3, and so on. A single word is trivially a word chain with k == 1.
+ * Return the length of the longest possible word chain with words chosen from the given list of words.
+ */
+
+class Solution {
+private:
+	static bool LT(const std::string& x, const std::string& y) {
+		if (y.length() - x.length() != 1)
+			return false;
+		bool ok = false;
+		for (int i = 0, j = 0; i < x.length(); ++i, ++j) {
+			if (x[i] == y[j])
+				continue;
+			if (ok)
+				return false;
+			ok = true;
+			--i;
+		}
+		return true;
+	}
+
+public:
+	static int longestStrChain(const std::vector<std::string>& words) {
+		const int n = words.size();
+		bool state[1001][1001]{};
+		for (int i = 0; i < n; ++i)
+			for (int j = 0; j < n; ++j)
+				if (LT(words[i], words[j]))
+					state[i][j] = true;
+		// {id, level}
+		int dp[1001]{};
+		std::function<int(int)> d = [&](int start) {
+			if (dp[start])
+				return dp[start];
+			int ret = 1;
+			for (int j = 0; j < n; ++j)
+				if (state[start][j])
+					ret = std::max(ret, 1 + d(j));
+			return dp[start] = ret;
+		};
+		int ans = 1;
+		for (int i = 0; i < n; ++i)
+			ans = std::max(ans, d(i));
+		return ans;
+	}
+};
+
+int main() {
+	// std::cout << (StrCount("ba") < StrCount("bda")) << "\n";
+	std::cout << Solution::longestStrChain({"qyssedya","pabouk","mjwdrbqwp","vylodpmwp","nfyqeowa","pu","paboukc","qssedya","lopmw","nfyqowa","vlodpmw","mwdrqwp","opmw","qsda","neo","qyssedhyac","pmw","lodpmw","mjwdrqwp","eo","nfqwa","pabuk","nfyqwa","qssdya","qsdya","qyssedhya","pabu","nqwa","pabqoukc","pbu","mw","vlodpmwp","x","xr"}) << "\n";
+	// return 0;
+	std::cout << Solution::longestStrChain({"a","b","ba","bca","bda","bdca"}) << "\n";
+	std::cout << Solution::longestStrChain({"xbc","pcxbcf","xb","cxbc","pcxbc"}) << "\n";
+	std::cout << Solution::longestStrChain({"abcd","dbqca"}) << "\n";
+	return 0;
+}
diff --git a/cpp/2206/CMakeLists.txt b/cpp/2206/CMakeLists.txt
index 9b45ed7..9f31d6f 100644
--- a/cpp/2206/CMakeLists.txt
+++ b/cpp/2206/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2206)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2206 220614.cpp)
+ADD_EXECUTABLE(2206 220615.cpp)