diff --git a/cpp/2210/221022.cpp b/cpp/2210/221022.cpp
new file mode 100644
index 0000000..a137c8d
--- /dev/null
+++ b/cpp/2210/221022.cpp
@@ -0,0 +1,84 @@
+#include <string>
+#include <iostream>
+
+/**
+ * 76. Minimum Window Substring
+ *
+ * Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return the empty string "".
+ * The testcases will be generated such that the answer is unique.
+ * A substring is a contiguous sequence of characters within the string.
+ */
+
+class Solution {
+private:
+	static inline int pos_of(char ch) {
+		return (ch > 'Z') ? (ch - 'a') : (ch - 'A' + 26);
+	}
+
+public:
+	static std::string minWindow(const std::string& s, const std::string& t) {
+		int m = s.length(), n = t.length();
+		const char* sp = s.c_str();
+		const char* tp = t.c_str();
+		if (m < n)
+			return "";
+
+		int seg_tree[128]{};
+		for (int i = 0; i < m; ++i)
+			++seg_tree[pos_of(sp[i])];
+		for (int i = 0; i < n; ++i)
+			++seg_tree[64 + pos_of(tp[i])];
+		for (int i = 0; i < 52; ++i)
+			if (seg_tree[i] < seg_tree[64 + i])
+				return "";
+
+		// Initial build of seg tree
+		for (int i = 0; i < n; ++i)
+			--seg_tree[64 + pos_of(sp[i])];
+		for (int i = 64; --i; )
+			seg_tree[i] = std::max(seg_tree[i << 1], seg_tree[i << 1 | 1]);
+		if (seg_tree[1] <= 0)
+			return s.substr(0, n);
+
+		// gradually expand & shrink
+		int L = 0, R = n, minL = 0x7FFFFFFF, mL, mR; // L inclusive, R exclusive
+		std::string ret;
+		while (R < m) {
+			// R+
+			for (; R < m && seg_tree[1] > 0; ++R) {
+				int p = pos_of(sp[R]) + 64;
+				--seg_tree[p];
+				// Update tree
+				while (p >>= 1)
+					seg_tree[p] = std::max(seg_tree[p << 1], seg_tree[p << 1 | 1]);
+			}
+
+			// L+
+			for (; L + n <= R; ++L) {
+				int p = pos_of(sp[L]) + 64;
+				if (seg_tree[p] >= 0)
+					break;
+				++seg_tree[p];
+			}
+
+			// Update tree after L+ at once
+			for (int i = 64; --i; )
+				seg_tree[i] = std::max(seg_tree[i << 1], seg_tree[i << 1 | 1]);
+
+			if (seg_tree[1] <= 0 && minL > R - L && R - L > 0)
+				minL = (mR = R) - (mL = L);
+
+			// Force update L
+			int p = pos_of(sp[L++]) + 64;
+			++seg_tree[p];
+			while (p >>= 1)
+				seg_tree[p] = std::max(seg_tree[p << 1], seg_tree[p << 1 | 1]);
+		}
+		return s.substr(mL, mR - mL);
+	}
+};
+
+int main() {
+	std::cout << Solution::minWindow("acbdbaab", "aabd") << "\n";
+	return 0;
+}
diff --git a/cpp/2210/CMakeLists.txt b/cpp/2210/CMakeLists.txt
index 45b05cf..2aa7491 100644
--- a/cpp/2210/CMakeLists.txt
+++ b/cpp/2210/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2210)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2210 221022-CN.cpp)
+ADD_EXECUTABLE(2210 221022.cpp)