diff --git a/2201/220123-CN.cpp b/2201/220123-CN.cpp
new file mode 100644
index 0000000..8ba7782
--- /dev/null
+++ b/2201/220123-CN.cpp
@@ -0,0 +1,204 @@
+#include <vector>
+#include <algorithm>
+#include <iostream>
+#include <chrono>
+#include <unordered_set>
+#include <set>
+#include <unordered_map>
+
+class StockPrice {
+private:
+	std::unordered_map<int, int> m;
+	std::multiset<int> min;
+	int currentTS = -1, currentPrice = -1;
+public:
+	StockPrice() = default;
+
+	void update(int timestamp, int price) {
+		if (timestamp >= currentTS) {
+			currentTS = timestamp;
+			currentPrice = price;
+		}
+		if (m.count(timestamp)) {
+			min.erase(min.find(m[timestamp]));
+		}
+		m[timestamp] = price;
+		min.insert(price);
+	}
+
+	int current() const {
+		return currentPrice;
+	}
+
+	int maximum() const {
+		return *min.rbegin();
+	}
+
+	int minimum() const {
+		return *min.begin();
+	}
+};
+
+class StockPriceHashMap {
+private:
+	int currentTS = -1, currentPrice = -1;
+	bool updatedMax = false, updatedMin = false;
+	int max = -1, min = 0x7FFFFFFF, maxTS = -1, minTS = -1;
+	std::unordered_map<int, int> m;
+public:
+	StockPriceHashMap() = default;
+
+	void update(int timestamp, int price) {
+		if (timestamp >= currentTS) {
+			currentTS = timestamp;
+			currentPrice = price;
+		}
+		m[timestamp] = price;
+		if (price >= max || maxTS == timestamp)
+			updatedMax = true;
+		if (price <= min || minTS == timestamp)
+			updatedMin = true;
+	}
+
+	int current() const {
+		return currentPrice;
+	}
+
+	int maximum() {
+		if (!updatedMax)
+			return max;
+		updatedMax = false;
+		max = -1;
+		for (const auto& i : m) {
+			if (i.second > max) {
+				maxTS = i.first;
+				max = i.second;
+			}
+		}
+		return max;
+	}
+
+	int minimum() {
+		if (!updatedMin)
+			return min;
+		updatedMin = false;
+		min = 0x7FFFFFFF;
+		for (const auto& i : m) {
+			if (i.second < min) {
+				minTS = i.first;
+				min = i.second;
+			}
+		}
+		return min;
+	}
+};
+
+class StockPriceHeap {
+	std::vector<std::pair<int, int>> maxHeap, minHeap;
+	int currentTS = -1, currentPrice = -1;
+	std::unordered_set<int> involvedTS;
+
+	static constexpr inline int father(int n) {
+		return ((n + 1) >> 1) - 1;
+	}
+
+	static constexpr inline int LChild(int n) {
+		return ((n + 1) << 1) - 1;
+	}
+
+	static constexpr inline int RChild(int n) {
+		return (n + 1) << 1;
+	}
+
+public:
+	StockPriceHeap() = default;
+
+	void update(int timestamp, int price) {
+		if (timestamp >= currentTS) {
+			currentTS = timestamp;
+			currentPrice = price;
+		}
+
+		// Search in minHeap
+		auto f = [timestamp, price, this](std::vector<std::pair<int, int>>& heap, auto cmp) {
+			int n = heap.size(), pos = n;
+			if (!this->involvedTS.count(timestamp)) {
+				// insert into heap;
+				heap.emplace_back(timestamp, price);
+			} else {
+				for (int i = 0; i < n; ++i) {
+					if (heap[i].first == timestamp) {
+						if (heap[i].second == price) {
+							// Found not changed, return immediately
+							return;
+						}
+						heap[i].second = price;
+						pos = i;
+						break;
+					}
+				}
+			}
+			// always treat heap as a maximum heap
+			// std::make_heap(heap.begin(), heap.end(), cmp);
+			while (pos && cmp(heap[father(pos)], heap[pos])) { // swap with father
+				std::swap(heap[pos], heap[father(pos)]);
+				pos = father(pos);
+			}
+			while (true) { // swap with children
+				int LR = 0;
+				if (LChild(pos) < n && cmp(heap[pos], heap[LChild(pos)]))
+					LR = -1;
+				if (RChild(pos) < n && cmp(LR ? heap[LChild(pos)] : heap[pos], heap[RChild(pos)]))
+					LR = 1;
+				if (!LR)
+					break;
+				std::swap(heap[pos], LR == 1 ? heap[RChild(pos)] : heap[LChild(pos)]);
+				pos = LR == 1 ? RChild(pos) : LChild(pos);
+			}
+		};
+
+		f(minHeap, [](const std::pair<int, int>& x, const std::pair<int, int>& y) { return x.second > y.second; });
+		f(maxHeap, [](const std::pair<int, int>& x, const std::pair<int, int>& y) { return x.second < y.second; });
+		involvedTS.insert(timestamp);
+	}
+
+	int current() const {
+		return currentPrice;
+	}
+
+	int maximum() const {
+		return maxHeap[0].second;
+	}
+
+	int minimum() const {
+		return minHeap[0].second;
+	}
+};
+
+int main() {
+	StockPrice solver;
+	/*
+	solver.update(1, 10);
+	solver.update(2, 5);
+	std::cout << "Current = " << solver.current() << std::endl;
+	std::cout << "Maximum = " << solver.maximum() << std::endl;
+	solver.update(1, 3);
+	std::cout << "Maximum = " << solver.maximum() << std::endl;
+	solver.update(4, 2);
+	std::cout << "Minimum = " << solver.minimum() << std::endl;
+	 */
+
+	auto begin = std::chrono::high_resolution_clock::now();
+	for (int i = 1; i <= 20000; ++i) {
+		solver.update(i, i);
+	}
+	for (int i = 1; i <= 10000; ++i) {
+		solver.update(i << 1, 1000000000);
+		solver.maximum();
+		solver.update((i << 1) + 1, 1000000000);
+		solver.minimum();
+	}
+	auto end = std::chrono::high_resolution_clock::now();
+	std::cout << "Time elapsed: " << std::chrono::duration_cast<std::chrono::milliseconds>(end - begin).count() << " ms\n";
+	return 0;
+}
diff --git a/2201/CMakeLists.txt b/2201/CMakeLists.txt
index afb2ca4..f6bfbfa 100644
--- a/2201/CMakeLists.txt
+++ b/2201/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2201)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2201 220122.cpp)
+ADD_EXECUTABLE(2201 220123-CN.cpp)